Full opinion text
MEMORANDUM AND ORDER ZOBEL, District Judge. Introduction.....................................................................95 Background and Procedural History................................................96 Content Delivery Service Providers.............................................96 Operation of the Parties’ Content Delivery Services...............................96 Akamai’s '703 Patent.........................................................97 The Farber '598 Patent.......................................................98 Sandpiper’s Footprint System .................................................98 The Digital Island and Speedera Patent Infringement Lawsuits....................99 The Instant Lawsuit.........................................................100 Discussion......................................................................100 Inequitable Conduct During Prosecution of the '703 Patent.......................100 The Legal Standard for Inequitable Conduct...............................101 Materiality........................................................101 Intent............................................................101 Evidentiary Rulings.....................................................101 DX1209 — Sandpiper Web Site Images ................................101 PX1004A — Limelight’s Markman Brief in the Level 3 Lawsuit...........103 DX1228 — Leighton’s Testimony in the Digital Island Trial...............104 The Allegedly Withheld Information ......................................104 Materiality........................................................104 Intent ............................................................108 Limelight’s Defenses of Laches and Equitable Estoppel..........................110 Legal Standard.........................................................110 Laches............................................................110 Equitable Estoppel.................................................Ill Factual Background ....................................................Ill Discussion.............................................................113 Laches............................................................113 Equitable Estoppel.................................................115 Unclean Hands.............................................................116 Limelight’s Motion for Reconsideration........................................116 BMC Resources........................................................117 The Jury Instructions in the Instant Case..................................118 Muniauction...........................................................119 Vicarious Liability..................................................119 The Significance of Muniauction.....................................120 Conclusion......................................................................123 I. Introduction Defendant Limelight Networks, Inc. (“Limelight”) seeks relief from a jury finding of patent infringement and an award of $45.5 million in damages to plaintiffs Akamai Technologies, Inc., and the Massachusetts Institute of Technology (hereinafter the singular “Akamai”) based on the defenses of inequitable conduct, laches, equitable estoppel and unclean hands. It also moves for reconsideration of my earlier denial of its motion for judgment as a matter of law (“JMOL”). After careful consideration of the evidence presented at the November 2008 bench trial and the arguments in the parties’ papers, I hold that Limelight has failed to prove that Akamai’s conduct was so egregious that its patent rights should not be enforced. However, based on a clarification in the standard for a finding of joint infringement articulated by the Federal Circuit after the jury trial, Limelight is entitled to JMOL on the issue of infringement. II. Background and Procedural History A. Content Delivery Service Providers Both Akamai and Limelight provide Internet content delivery services to their customers, content providers who maintain, inter alia, news and entertainment web sites that supply content to end users’ web browsers. Without such a service, a content provider must distribute all its content from its own web servers. This requires the content provider to purchase and maintain servers and telecommunications bandwidth to handle the worst case load, and even then it may be overwhelmed by an unanticipated event, such as a major national disaster, or even a planned event which draws a large number of viewers, such as the Super Bowl. In addition, end users located far from the content provider’s servers may experience poor performance due to Internet delays and congestion. Content service providers Akamai and Limelight both maintain their own content delivery network (“CDN”) consisting of hundreds or thousands of servers located in multiple locations across the United States and around the world. Once a content provider has contracted for content delivery services, a portion of its web content, typically large data files such as images, video and/or sound, is supplied by the CDN from a server located close to the end user rather than from the content provider’s servers. Because a content delivery service aggregates the data demands of multiple content providers with differing peak usage patterns and serves that content from multiple servers in multiple locations, it is less likely to slow down or fail when an event creates a high demand for particular content. In addition, since content is supplied from a server close to the end user, that content is less likely to be affected by Internet congestion or breakdowns. The result is that the content provider can obtain the capacity to service its end users under worst case demand conditions without having to pay for capacity that is idle much of the time. B. Operation of the Parties’ Content Delivery Services A web page typically consists of text interspersed with various types of content such as images, video and sound, which are referred to as page objects. The web page, as well as the page objects, are stored on the content provider’s web server. The page objects are normally not included within the web page itself, rather the web page consists of only the text on the page along with links (i.e. an Internet address) pointing to the page objects. Upon receiving a request for a web page, the content provider’s web server returns the web page containing these links to the end user’s web browser. The end user’s web browser then uses these links to request each page object from the content provider’s server until all the objects have been retrieved and the web page fully rendered. To utilize Akamai’s or Limelight’s content delivery service, the content provider modifies its web pages so that the links, or URLs, to the page objects point to the content service provider’s servers, not its own. The end user’s browser fetches the initial web page from the content provider’s server and then uses the returned links to request the other objects on the page from the content service provider’s servers. The content delivery service provider replicates these page objects on some or all of its servers and directs the end user’s request for an object to an appropriate server. Thus, only the initial page is supplied by the content provider; the remaining page objects are served by the content delivery service provider’s web servers. Because the initial page supplied by the content provider is relatively small compared to the size of the page objects, the majority of the information on the page is served by the content delivery service provider. C. Akamai’s '703 Patent On July 14, 1998, Akamai filed a provisional application for what would become the '703 patent. The disclosures in this patent form the basis for Akamai’s Free-Flow content delivery service. The utility application was filed on May 19, 1999, and Akamai filed a petition to make special (“PTMS”) with the Patent and Trademark Office (“PTO”) in September 1999 to expedite the examination of its application. See 37 C.F.R. § 1.102 (1999). The PTO allowed the PTMS the following month, then, after a single office action in February 2000, allowed the application in April 2000. The patent issued on August 22, 2000. The '703 patent claims systems and methods for replicating page objects among a distributed set of content delivery service provider servers and redirecting end user requests for those objects to a particular content server. The specification describes, inter alia, a modification to the Internet’s address lookup system, the Domain Name System (“DNS”), to accomplish this redirection. The DNS consists of a set of computers known as domain name servers which translate (“resolve”) textual names of computers on the Internet (“hostnames”) into numerical Internet addresses (“IP addresses”). The '703 patent describes the use of virtual hostnames which do not resolve to the IP address of a particular server; rather, in conjunction with the modified DNS described in the patent, the virtual hostname resolves to the IP address of a server containing the page object which is near the end user, has the page object and is not overloaded. Thus, a given virtual hostname could resolve to the IP address of servers at opposite ends of the country or around the world depending on the location of the end user, the location of the content and the delays in routing to the available servers. The two independent claims asserted in the instant case, however, do not require either the use of virtual hostnames or a modified DNS. They do require modifying the links to at least some of the page objects, termed “tagging” in the patent, so that requests for those objects resolve to a content server in a domain other than the content provider’s domain. In this context, a domain is an organization’s unique name on the Internet, for example “akamai.com” or “limelightnetworks.com.” In addition, one of the asserted claims, claim 19, also requires the initial page to be served from the content provider’s domain. The tagging described in the '703 patent adds or “prepends” the hostname of the content service provider’s server to the original URL used to retrieve the page object from the content provider’s server. Including the original URL in the tagged link provides the content service provider’s server with the information necessary to retrieve the object from the content provider’s server if it is not already stored (“cached”) locally. Once the content service provider’s server fetches an object from the content provider’s server, it caches it locally so it is available for subsequent requests for that object. D. The Farber '598 Patent On February 10, 1998, Sandpiper Networks, Inc. (“Sandpiper”) filed a United States patent application for a content delivery system. Just under a year later, Sandpiper filed an international patent application with the World Intellectual Property Organization under the Patent Cooperation Treaty (“PCT Application”) containing the same specification as its earlier United States application. The PCT Application was published on August 12, 1999. Although Sandpiper’s United States application was filed before Akamai’s provisional application, Sandpiper’s patent, United States Patent No. 6,185,-598 (the “'598 patent”), did not issue until February 6, 2001, after the '703 patent issued. The '598 patent claims systems and methods for a content delivery system similar to those claimed by Akamai. However, rather than use DNS to redirect an end user to an appropriate content server (termed a “repeater” in the '598 patent), the patent adds a component called a reflector to the content provider’s server to redirect requests for page objects (termed “resources”) to be served from a repeater. In one embodiment, the reflector redirects a resource by rewriting the link to the resource to create a new link which designates the repeater instead of the content provider’s server. The rewritten link consists of an identifier for the repeater followed by the original URL to the resource. This identifier can be the hostname of the repeater or the actual IP address of the repeater. The end user’s browser then uses the rewritten link to request the resource from the repeater. If the resource is available locally on the repeater, it is returned to the end user. If the resource is not already on the repeater, the repeater uses the original URL portion of the rewritten link to fetch the resource from the content provider’s server, returns it to the end user and caches it locally for future requests. E. Sandpiper’s Footprint System Sandpiper introduced its content delivery service, named Footprint, in September 1998. This initial system (hereinafter “Footprint 1.0”) required reflector software running on the content provider’s server to intercept end user requests for content and redirect them to Sandpiper’s content servers. In spring of 1999, Sandpiper modified its system to use DNS, rather than the redirector software, to redirect end user requests for content. Akamai believed this new system (“Footprint 2.0”) was a direct copy of its then newly deployed content delivery system based on the '703 patent. F. The Digital Island and Speedera Patent Infringement Lawsuits In September 2000, Akamai filed suit against Digital Island, Inc. (“Digital Island”) alleging, inter alia, infringement of the '703 patent by Digital Island’s {nee Sandpiper’s) Footprint 2.0 system. On December 21, 2001, a jury found that the Footprint 2.0 system infringed claims 1, 3, 5, 9, 17, 18 and 22 of the '703 patent, but that claims 17, 18 and 22 were invalid as anticipated by Digital Island’s '598 patent or obvious in view of the '598 patent and a product by Cisco Systems, Inc., Distributed Director, disclosed in United States Patent No. 6,178,160. {See Civ. A. No. 00-11851-RWZ (D.Mass.), Docket #232.) The district court granted a permanent injunction based on the jury verdict. Digital Island appealed to the Court of Appeals for the Federal Circuit, arguing that claim 9 was not infringed and that claims 1, 3, 5, and 9 were invalid for anticipation and/or obviousness. In its opinion, the court described the history of Digital Island’s '598 patent and its Footprint systems: The '598 patent is directed to similar systems and methods [as the '703 patent] for increasing the accessibility of web pages on the Internet. The '598 patent was filed on February 10, 1998, and issued on February 6, 2001. Thus the '598 patent is prior art to the '703 patent pursuant to 35 U.S.C. § 102(e). C & W marketed and sold products embodying the '598 patent under the name “Footprint.” The relevant difference between the disclosure of the '598 patent and Akamai’s preferred embodiment disclosed in the '703 patent is the location of the load balancing software. Akamai’s preferred embodiment has the load balancing software installed at the DNS servers, while the '598 patent discloses installation of the load balancing software at the content provider, or origin, servers. The '598 patent does not disclose or fairly suggest that the load balancing software can be placed at the DNS servers. It is now understood that placement of the software at the DNS servers allows for load balancing during the resolving process, resulting in a more efficient system for accessing the proper information from the two server networks. Indeed, C & W later created a new product, “Footprint 2.0,” the systems subject to the permanent injunction, in which the load balancing software was installed at the DNS servers as opposed to the content provider servers. Footprint 2.0 replaced C & W’s Footprint product. Akamai Techs. Inc. v. Cable & Wireless Internet Servs., Inc., 344 F.3d 1186, 1190— 91 (Fed.Cir.2003) (footnote omitted). The Federal Circuit held that claims 1 and 3 of the '703 patent were invalid because they did not require that the load balancing software be placed at the DNS servers and thus were anticipated by the '598 patent. Id. at 1194-95. In February 2002, Akamai sued another competitor, Speedera Networks, Inc. (“Speedera”), alleging that Speedera’s Universal Delivery Network infringed several Akamai patents, including the '703 patent. (See Civ. A. No. 02-10188-RWZ (D.Mass.), Docket # 1.) The case settled in mid-2005 after the district court’s order on claim construction but before any other decision on the merits. G. The Instant Lawsuit Limelight began offering its content delivery services in late 2001. In the spring of 2004, Akamai and Limelight began a series of discussions concerning the possible acquisition of Limelight by Akamai. Ultimately, Akamai choose not to proceed with the proposed deal, and the discussions terminated in the fall of 2004. In early 2006, Akamai and Limelight again resumed acquisition discussions. However, on June 22, 2006, Limelight informed Akamai that it had found alternative funding and was no longer interested in being acquired. On the following day, Akamai filed the instant lawsuit against Limelight alleging patent infringement. On February 28, 2008, a jury found that Limelight infringed claims 19-21 and claim 34 of the '703 Patent and that none of the infringed claims were invalid due to anticipation, obviousness, indefiniteness, lack of enablement or written description. The jury awarded Akamai damages of $41.5M based on lost profits and reasonable royalty from April 2005 through December 31, 2007, plus prejudgment interest, along with price erosion damages in the amount of $4M. (See Jury Verdict (Docket # 287).) The parties filed a flurry of post-trial motions. Akamai renewed its motion for partial summary judgment on Limelight’s equitable defenses of laches, equitable estoppel and unclean hands, moved for summary judgment on Limelight’s defense of inequitable conduct and sought a permanent injunction. Limelight moved for a new trial and for a judgment of obviousness and renewed its motion for JMOL on grounds of noninfringement and invalidity. After briefing and a hearing, I denied all six motions, including Akamai’s motion for a permanent injunction, which was premature in light of the scheduled bench trial. Shortly thereafter, Limelight moved for reconsideration on the court’s denial of its motion for JMOL, citing a newly announced Federal Circuit decision. (See Docket # 377.) After a delay requested by the parties, the court held a three-day bench trial in November 2008 on Limelight’s remaining equitable defenses. III. Discussion A. Inequitable Conduct During Prosecution of the '703 Patent Limelight asserts that the applicants for the '703 patent and/or their attorney: (1) had a duty to, but intentionally failed to, investigate the prior art of their key competitor Sandpiper; and (2) intentionally withheld material from the PTO concerning Sandpiper’s Footprint 1.0 CDN. It claims that these actions breached the duty of candor and good faith owed to the PTO and thereby constitute inequitable conduct rendering the patent unenforceable. Although I find that the information that was not disclosed was material, Limelight has failed to prove the requisite intent necessary to find inequitable conduct. 1. The Legal Standard for Inequitable Conduct Applicants have a duty to prosecute patent applications with candor, good faith, and honesty. Duro-Last, Inc. v. Custom Seal, Inc., 321 F.3d 1098, 1099 (Fed.Cir.2003); see also 37 C.F.R. § 1.56. A breach of this duty constitutes inequitable conduct and renders a patent unenforceable. See Impax Labs., Inc. v. Aventis Pharms., Inc., 468 F.3d 1366, 1374 (Fed.Cir.2006). To prove inequitable conduct, “the alleged infringer must provide clear and convincing evidence of (1) affirmative misrepresentations of a material fact, failure to disclose material information, or submission of false material information and (2) an intent to deceive.” Id. The analysis of inequitable conduct is a two-step process. First, the court must determine whether both the materiality of the information and the intent to deceive have been established. Bristol-Myers Squibb Co. v. Rhone-Poulenc Rorer, Inc., 326 F.3d 1226, 1234 (Fed.Cir.2003). If so, it must then “weigh them to determine whether the equities warrant a conclusion that inequitable conduct occurred.” Id. (quoting Molins PLC v. Textron, Inc., 48 F.3d 1172, 1178 (Fed.Cir.1995)). In balancing, a greater showing of one factor can compensate for a lesser showing of the other. Id. a. Materiality Information is material if a reasonable examiner would consider it important in deciding whether to allow the patent application. Digital Control, Inc. v. Charles Mach. Works, 437 F.3d 1309, 1314 (Fed.Cir.2006) (citations omitted). Information can be material even though disclosure of it would not render the invention unpatentable. Id. at 1318. However, pri- or art that is merely cumulative or less pertinent than information considered by the examiner is not considered material in analyzing a claim of inequitable conduct. Id. at 1319. b. Intent The evidence must also support a finding that the material information was withheld with an intent to deceive or mislead the PTO. Abbott Labs. v. Sandoz, Inc., 544 F.3d 1341, 1356 (Fed.Cir.2008). “[T]he involved conduct, viewed in light of all the evidence, including evidence of good faith, must indicate sufficient culpability to require a finding of intent to deceive.” Impax Labs., 468 F.3d at 1375 (citation omitted). Where the alleged conduct is the nondisclosure of information, there must be clear1 and convincing evidence that the applicant made a deliberate decision to withhold the information from the PTO. Molins, 48 F.3d at 1181. 2. Evidentiary Rulings a. DX1209 — Sandpiper Web Site Images As discussed infra, one of the factual issues relevant to the allegations of inequitable conduct is what Akamai knew about Sandpiper’s Footprint system and when it knew it. Daniel Lewin (“Lewin”), one of the inventors of the '703 patent, admitted studying Sandpiper’s web site frequently during the pendency of the '703 application. At the bench trial, Limelight moved to admit printouts of Sandpiper’s web site from January and May 1999 (DX1209), which included several press releases describing the Footprint system, to show the extent of Akamai’s knowledge at the time. I admitted the exhibit de bene, and the parties have submitted briefs on its admissibility. In two separate written lists of objections to Limelight’s exhibit list, provided to Limelight before the November bench trial, Akamai objected to DX1209 on grounds of relevance and hearsay. (See Docket # 395, Exs. 1, 2.) It argues that the press releases are not relevant because there is no evidence that the inventors of the '703 patent ever saw them. However, Lewin testified that in August or September of 1998 a friend sent him the URL for Sandpiper’s web site and suggested that he take a look at what it was doing. He further testified that he and others at Akamai read the Web site in great detail, which had an overview of what they were doing, what the business was, who the people were that were involved in the company, overall descriptions of what the benefits to a customer were. Their network infrastructure was on the Web site. (Lewin Dep. 80:5-11, Jan. 18, 2001.) At that time, Lewin discussed Sandpiper as a potential competitor with Tom Leighton (“Leighton”), the other inventor of the '703 patent (collectively with Lewin, the “Inventors”), as well as with other Akamai personnel. He continued to monitor Sandpiper’s web site, agreeing that he “looked at the Sandpiper Web page almost daily.” (Id. at 94:5-7.) Leighton testified that he first learned about Sandpiper in the fall of 1998 “as a consequence of the September 28th press release.” (Trial Tr. Day 2, 109:18-22, Nov. 13, 2008.) He also explained that Akamai deduced the operation of Sandpiper’s system by looking at how it delivered Sandpiper’s own web site. Several of the press releases in the proffered exhibit include a description of Sandpiper as “a provider of adaptive content distribution services” and describe Sandpiper’s technology as “optimizing] network performance by migrating content based on network conditions, content popularity and traffic loads.” (e.g., DX1209 at L3-AKLL-000007.) In addition, a September 28, 1998, press release describes the Footprint “distribution network” as “patent-pending.” (Id. at L3-AKLL000010.) The evidence proffered supports the conclusion that both press releases were made available on the web site shortly after release. (Compare id. at L3-AKLL-000004 (list of Sandpiper press releases on web site as of Jan. 13,1999), with id. at L3-AKLL-000025 (list of Sandpiper press releases on web site as of May 2, 1999).) Lewin’s and Leighton’s testimony, that they paid close attention to Sandpiper’s web site beginning in fall of 1998, permits the inference, which I draw, that one or both of them read the press releases contained therein. Therefore, exhibit DX1209 is relevant to the issue of what the Inventors knew about Sandpiper and its Footprint system during the prosecution of the '703 patent. See Fed. R. Evid 401. Akamai’s second objection, that the Sandpiper web site printouts are hearsay, fails because they are not offered for the truth of the information contained within. Rather, Limelight seeks to show the Inventors’ knowledge that in late 1998 and early 1999 Sandpiper claimed to have a content delivery system that took content popularity, network loads and congestion into account in delivering content, and that it had submitted a patent application for some part of that system. Whether these claims were actually true is immaterial to the issue of inequitable conduct by Akamai. Therefore, both of Akamai’s pretrial objections to the exhibits are overruled. On the first day of the bench trial, however, Akamai raised yet another objection, namely, that “the testimony that authenticates these press releases is itself hearsay.” (Trial. Tr. Day 1, 52, Nov. 12, 2008.) Before the trial, in September 2008, Limelight, to authenticate DX1209, had provided excerpts from a Rule 30(b)(6) deposition of Andrew Swart (“Swart”), a former Sandpiper employee, taken in a lawsuit between Limelight and Level 3 Communications, LLC (“Level 3”). Akamai objected because it was not a party to that lawsuit and therefore did not have an opportunity to cross-examine Swart. In response, Limelight attempted to depose Swart again, this time with Akamai present. Level 3, however, provided not Swart, but Joseph Lawrence (“Lawrence”), a Level 3 employee, as its 30(b)(6) witness. (See Docket # 395, Exs. 6, 7.) Lawrence authenticated the web site printouts and the press releases based on discussions with Swart and another former Sandpiper employee, Will Crowder. Akamai now objects to Lawrence’s authentication because it is based on hearsay, not personal knowledge, and Level 3 is not a party-opponent. While Akamai did object to Lawrence’s deposition testimony as hearsay two weeks before the trial, it did not put Limelight on notice that it objected to the authenticity of DX1209. It therefore waived that objection. See Fed.R.Civ.P. 26(a)(3)(B) (waiving any objection to exhibits disclosed prior to trial other than relevance, prejudice or confusion). DX1209, therefore, is admitted for the purpose of showing what information was on the Sandpiper web site in late 1998 and early 1999 when Lewin testified he was viewing the site. b. PX1004A—Limelight’s Markman Brief in the Level 3 Lawsuit Akamai seeks to introduce a Markman brief that Limelight filed in an unrelated case as an admission by Limelight that the specification of the Farber '598 patent describes a system significantly different from that described by the '703 patent. In particular, it argues that Limelight’s adoption of portions of an email memorandum Farber sent during the pendency of the '703 application establishes the authenticity and admissibility of that memorandum. Limelight objected to the admission of both the brief and the memorandum, and I invited Akamai to provide additional briefing on their admissibility post-trial. (See Trial Tr. Day 2, 53:23-25, Nov. 13, 2008.) Akamai has provided a paragraph of explanation why it believes these documents are admissible, citing only to Fed.R.Evid. 801(d)(2) (admissions by a party opponent are not hearsay). (See PX1004A, flysheet.) The objection to this exhibit is sustained both because the briefing is inadequate to resolve the legal issue and because this evidence is, in any event, either not relevant to the issue of inequitable conduct or cumulative of other testimony. c. DX1228 — Leighton’s Testimony in the Digital Island Trial At the November 2008 bench trial, Leighton testified that Akamai’s investigation into the operation of the Footprint 1.0 system showed that it used IP addresses, not hostnames, to redirect requests for page objects from the content provider’s server to the content service provider’s servers. He denied both knowing that the Footprint 1.0 system could alternately use hostnames to redirect object requests or having seen the Sandpiper PCT application, which described the use of hostnames as well as IP addresses, prior to the issuance of the '703 patent. On cross-examination, Limelight attempted to impeach Leighton’s direct testimony using Farber’s deposition and testimony from the 2001 Digital Island trial describing the Footprint 1.0 system. I allowed the questioning de bene over Akamai’s objection. I now overrule that objection. Limelight post trial seeks to introduce a portion of Leighton’s testimony from the Digital Island lawsuit to attempt to show that he learned additional information about Footprint 1.0 during the pendency of the '703 application. Akamai objects because by not identifying and offering this testimony at the bench trial, Limelight denied it the opportunity to counter-designate relevant testimony and denied Leigh-ton the opportunity to explain his prior testimony. For reasons similar to those discussed supra Part III.A.2.a, overruling Akamai’s objection to the Sandpiper web site printouts, its objection to this evidence is sustained. 3. The Allegedly Withheld Information Limelight alleges that, during the pendency of the '703 application, Akamai was aware of Sandpiper and its Footprint 1.0 system, which, Limelight argues, is an embodiment of the '598 Patent, but failed to disclose this information to the PTO. Limelight further asserts that Akamai was aware that Sandpiper had filed a patent covering the Footprint 1.0 technology and, therefore, had a duty report this information to the PTO or at least conduct an investigation into Sandpiper as part of its PTMS. a. Materiality Limelight argues that the '598 patent, and thus the Footprint 1.0 system, was material because the Federal Circuit later held that claims 1 and 3 of the '703 patent were invalid as anticipated by the '598 patent. Akamai responds that the disclosures in the '598 patent were not material because they were cumulative of other information Akamai provided to the PTO. In addition, to the extent the Footprint 1.0 system was an embodiment of that patent, Akamai argues that it did not include the features that the Federal Circuit relied on to find anticipation. In particular, it asserts that the Footprint 1.0 system prepended IP addresses, not host-names, and therefore did not require the use of DNS, both limitations of the claims ruled invalid as anticipated. See Akamai Techs., 344 F.3d at 1192 (a prior art reference is anticipating if it “discloses each and every limitation of the claim expressly or inherently”). According to the testimony and evidence, the Inventors understood that Sandpiper’s Footprint 1.0 system was a framework for delivering web content. As such it attempted to solve the same general problem Akamai was addressing, namely, reducing the bottleneck created by serving all content from a single server while avoiding the limitations of then existing mirroring content delivery systems. Mirroring systems, which duplicate content on multiple servers, do not scale well because it becomes increasingly difficult to keep the content of all the systems synchronized as the number of servers increases. Footprint 1.0, like the system described in Akamai’s '703 patent, implemented a content delivery system that split delivery of the contents of a web page by serving the initial page from the content provider’s server, but some or all of the page objects from a server closer to the end user. Page splitting addresses the synchronization problem because the original web page need be kept up-to-date only on a single server, that of the content provider. By always fetching the initial page from the content provider’s server, a page-splitting system guarantees that the user receives the current content. In addition, both the Footprint 1.0 system and the disclosure in the '703 application replaced the URL to each page object with a rewritten URL that consisted of an identifier for an optimal content server followed by the original URL for the object. This preserves the original Internet address of the object in the new URL, enabling the content server to fetch the object from the content provider’s server if the object was not already cached locally. Therefore, unlike mirroring systems, these systems did not require that all content be copied to the content servers prior to the first end user request. This design ensures that any page objects updated by the content provider are migrated to the content service provider’s servers when requested by end users. The primary differences between the Footprint 1.0 system and that described in the '703 patent is that Footprint 1.0 prepended an IP address not a hostname, and the determination as to which content server to prepend was made at the content provider’s server by the reflector, not by the DNS system described in Akamai’s application. Nevertheless, Footprint 1.0 attempted to solve the same synchronization problem that the '703 sought to solve in much the same way. While much of the '703 patent focuses on the use of a virtual hostname and DNS to select an optimal content server, several of the claims of Akamai’s patent differ from the Footprint 1.0 system only in the use of a normal hostname rather than an IP address prepended to the original URL or by requiring the resolution of a hostname. {See, e.g., '703 patent claim 14; id. claim 23.) In addition, the Inventors viewed the Footprint 1.0 system as direct competition to their content delivery system, which was based on the invention claimed in the '703 patent, and they expended significant effort to investigate and reverse engineer the operation of this competing system. Given the similarity in the problem each system attempted to solve and in the operation of the respective systems, “a reasonable examiner would consider [Footprint 1.0] important in deciding whether to allow [Akamai’s] application to issue as a patent.” Digital Control, 437 F.3d at 1315. Thus, Sandpiper’s Footprint 1.0 system was material information that should have been disclosed to the PTO during the pendency of Akamai’s application, unless it was cumulative of other information provided. At the bench trial, Akamai’s expert, Kevin Jeffay (“Jeffay”), opined that the '598 patent, and thus its embodiment in the Footprint 1.0 system, was merely cumulative of other information Akamai included in its submissions to the PTO. In particular, he asserted that the Kriegsman and Kenner patents, which Akamai did provide to the PTO, disclosed all of the relevant features of the '598 patent. The Kriegsman patent, United States Patent No. 5,991,809 (the “'809 patent”) (PX1016), discloses a system consisting of a primary server and one or more secondary servers which miiTor static files copied from the primary server. When the primary server receives a request for data, it returns all the dynamic data files requested, then determines an optimum secondary server to serve each static data file. If a requested dynamic data file contains links to static data, software on the primary server replaces those links with new links pointing to the static data on the optimum secondary server. {See '809 patent, eol.9 11.61— 65.) However, unlike the disclosure in the '598 patent, the Kriegsman patent does not include the link to the original object in the rewritten link, and therefore the secondary server cannot use the URL of the requested object to request the object from the primary server if it is not stored locally. Rather, the patent describes a mirrored system in which the primary server copies static data to the secondary servers prior to redirecting users’ requests for static content to a secondary server. {See id. eol.6 1.67-col.71.9.) The Kenner patent, United States Patent No. 6,003,030 (the “'030 patent”) (PX1015), discloses a content delivery system primarily designed to serve video objects and which utilizes software installed on the end user’s computer (“Client Software”) to route requests for content to an optimal content server. Content to be served is copied from the original web site to the content servers prior to end user requests for content. When a user makes a request for content which is marked as also available on the content servers, the Client Software attempts to download the content from the optimal server by constructing a URL pointing to that content on the content servers. {See '030 patent, eol.15 11.4-10.) If the content is not available, the Client Software tries the next available content server. If the content is not found on any of the content servers, the Client Software retrieves it from the original content provider’s site. {See id. col. 15 11.18-24.) According to Jeffay, Kriegsman discloses all aspects of the '598 patent except for prepending the URL pointing to the original object on the content provider’s server to the rewritten URL and retrieving the object from the content provider’s server when it is not found on the content server. However, he asserts that these features are disclosed in the Kenner patent. Therefore, the disclosures of the '598 patent are, in his opinion, cumulative of those obtained by combining Kriegsman and Kenner. But see Molins, 48 F.3d at 1180 (noting that a withheld reference can be material when no single piece of cited prior art taught the combination present in the reference). Jeffay’s conclusion assumes that the URL created by the '030 patent’s Client Software to retrieve the object from a content server includes the original URL pointing to the object on the content provider’s server. The patent describes passing information to the end user, and thus to the Client Software, about whether content is available on a content server within a text construct known as an “EMBED” statement. The patent’s specification describes how it creates the URL to retrieve the object from a content server, termed a “Smart Mirror:” If the [page object] does not exist on the local computer, the player creates a new URL (step 78) in the following form: “http://”, plus the IP address of the selected Smart Mirror site stored in the configuration file, plus the path name to mirror files (e.g.”/pub/mirror/”), plus the name of the content provider taken from the “SM” parameter in the EMBED statement, plus the [page object] filename taken from the EMBED statement. ('030 patent col.15 11.4-10 (emphasis added).) If the content is not available on a content server, the Client Software retrieves it “from the original content provider’s site as specified directly by the EMBED statement.” (Id. col.15 11.21-24.) Jeffay opines that “the name of the content provider” refers to the hostname of the original server. However, this is not explicitly stated in the '030 patent and hostnames are not necessarily identical to the name of the content provider, for example, content provider Volkswagen uses the hostname www.vw.com. In addition, both the '598 patent and the '703 patent explicitly describe prepending the host-name of the content service provider’s server to the origin server and path to the original object and the Footprint 1.0 system prepended the IP address of a content server to the origin server and path to the original object. (See '598 patent col.8 11.26-35; '703 patent col.8 11.4-12; PX1009, 9-10.) The '030 patent, however, only describes appending the name of the content provider and the filename of the object, not the path to the original object. In addition, because the '030 patent does not require that a content server be able to retrieve objects which it does not already have mirrored, there is no reason to include the URL to the original object in the constructed URL. Therefore, the evidence is insufficient to conclude that the Kenner '030 patent discloses prepending the identifier of a content server to the URL of the original object as is disclosed in the '598 patent and as was observed by the Inventors in examining the operation of Footprint 1.0. Thus, the '598 patent and the Footprint 1.0 system are not cumulative of the combination of the Kriegsman and Kenner patents. In addition, neither Kenner nor Kriegsman disclose the technique described in the '598 patent in which content servers use the URL of the original object to retrieve the object if it is not already cached on the content server. In Kenner, it is the Client Software running on the end user’s computer that fetches the object if it is not found on any content server. (See '030 patent col.6 11.36-37, col.15 11.21-24.) Kriegsman is a mirrored system with data copied to the secondary (content) servers by the primary server before any requests for content are made; therefore, the patent does not contemplate a need to fetch an object in response to a user request to a secondary server. (See '809 patent col.3 11.45-48, col.6 1.67-col.7 1.5.) For all of these reasons, I find that the '598 patent was material because it contained prior art which was later found to have anticipated several claims of the '703 patent and was not cumulative of other information provided to the PTO during the prosecution of the '703 patent. See Fox Indus., Inc. v. Structural Pres. Sys., Inc., 922 F.2d 801, 804 (Fed.Cir.1990). I also find that the Footprint 1.0 system was not cumulative of other references provided to the PTO and thus was material for the reasons described supra. b. Intent Limelight argues that intent by the Inventors to withhold information from the PTO can be inferred from their careful examination of the Sandpiper web site, their investigation into the operation of the Footprint 1.0 system, the temporal proximity of Akamai’s PTMS following the publication of Sandpiper’s PCT application and the limited search Akamai conducted as part of that PTMS. Leighton testified that because the Footprint 1.0 system used IP addresses, not hostnames, it did not occur to him that it was relevant to Akamai’s efforts to patent its DNS-based system. He stated that he viewed the Sandpiper system as having many of the same deficiencies as the mirroring systems that Akamai was trying to correct, in particular, the bottleneck of having all redirection determinations made at the content provider’s server. Footprint 1.0 prepended IP addresses, so there was no way for Sandpiper to use DNS to distribute requests for page objects to other servers. Because he saw the use of DNS as fundamental to the Akamai invention, he did not consider disclosing Footprint 1.0 to the PTO. In addition, he testified that in late 1998 and early 1999 he was preoccupied with efforts to launch Akamai’s own content delivery service. When Sandpiper released Footprint 2.0 after Akamai launched its service, Leigh-ton believed Sandpiper had copied the Akamai system in response to the problems created by the centralization inherent in the architecture of the Footprint 1.0 system. Therefore, he did not consider Footprint 2.0 relevant to the disclosures in the '703 patent application; rather, he asked his patent counsel to investigate the possibility of an infringement claim against Sandpiper when Akamai’s patent finally issued. Finally, Leighton stated that he was unaware of Sandpiper’s PCT application or its United States patent application until after the '703 patent issued. Limelight disputes Leighton’s credibility. It points out that Sandpiper’s web site, which Akamai employees studied in detail, described Sandpiper’s technology as “patent-pending” and cites an Akamai competitive overview (PX1009) which, it asserts, shows that Akamai was aware that Footprint 1.0 used hostnames as well as IP addresses. While I find that Akamai employees, including Lewin, carefully examined Sandpiper’s web site and considered Sandpiper a serious competitor in the content distribution arena, there is no evidence that anyone who saw the Sandpiper press releases recognized the “patent-pending” statement as relevant to Akamai’s own patent application. As to Akamai’s competitive overview, dated September 30, 1999; it only describes Footprint 1.0 as prepending IP addresses. (See PX1009, 9 (“[Sandpiper 1.0] redirects] inbound user requests ... using proprietary routing tables that provide IP addresses .... ”); id. at 10 (“URLs that used [Footprint 1.0] for content delivery typically appear as an IP address followed by a standard URL.”).) The document also notes that “nearly all customers use Footprint 2.0,” the copy of Akamai’s system. (Id. at 9.) In addition, Lewin testified in an earlier deposition that Footprint 1.0 only prepended IP addresses. There is no evidence that the Inventors were aware that Sandpiper described prepending hostnames as a separate embodiment of its invention until they read it in the specification for the PCT application or the '598 patent. I find credible Leighton’s testimony that the Inventors were not aware of Sandpiper’s PCT application until after the '703 patent issued. The coincidence of Akamai’s decision to file its PTMS six weeks after the PCT application was published is not enough to persuade me otherwise. Given the central importance of DNS to the disclosures of the '703 patent and the operation of Footprint 1.0 which only prepended IP addresses, together with the pressures of creating a startup company, I am persuaded that Leighton did not deliberately fail to disclose Footprint 1.0 to the PTO. There is also no evidence that Lewin intentionally failed to disclose Footprint 1.0, only that he studied Sandpiper’s web site and therefore may have read Sandpiper’s claim that its technology was patent-pending. Akamai’s patent attorney, David Judson (“Judson”), testified that he first became aware of Sandpiper in summer of 1999 because Akamai believed that Footprint 2.0 was a copy of its system. As a result, his investigations into Sandpiper looked to a possible infringement lawsuit, not possible prior art. Although he became aware of the Footprint 1.0 system as a result of his investigation, I credit his testimony that his focus was on infringement by the Footprint 2.0 system. With respect to the prosecution of the '703 patent, Judson testified that he made two searches in preparation for the PTMS. First, he conducted a keyword search on a patent database, possibly the IBM patent database; however, he was not sure at trial. He is unable to locate any notes or records of the search. This search did not return Sandpiper because at the time the company had no United States patents. In addition, he searched a patent assignment database for five companies identified by Leighton in the provisional application as involved in the problem of content delivery. Because the provisional application had been filed before Akamai became aware of Sandpiper, it was not one of the five companies listed and therefore was not among the companies searched. Judson testified that his practice was not to search a database of foreign patent assignments, which conceivably might have found Sandpiper’s PCT application. Finally, he conducted a manual search through other patents he had in his office that he thought might be relevant. Akamai did disclose approximately 50 references during the prosecution of the '703 case, including the Kriegsman and Kenner patents as well as a paper by Amir, et al. The Amir paper appeared on its face to have been published after the '703 application priority date, but Akamai disclosed to the PTO that it may have been publicly available before that date. At the jury trial, Limelight relied on the Kenner patent and a presentation by Peterson, one of the authors of the Amir paper, to argue that the '703 patent was obvious. Judson testified that he was not aware of the Sandpiper PCT application or the '598 patent until after the '703 patent issued. In hindsight, Judson probably should have disclosed the existence of Sandpiper’s Footprint system to the PTO, or at least included Sandpiper in his searches, and the lack of records concerning his PTMS search investigation is troubling. Nonetheless, I credit his testimony that by the time he became aware of Sandpiper he viewed it as a copier not an innovator. See Molins, 48 F.3d at 1181 (expressing concern about “the ease with which a relatively routine act of patent prosecution can be portrayed as intended to mislead or deceive”). Limelight argues that intent can be inferred from Akamai’s failure to disclose the Footprint 1.0 system to the PTO, its decision to file a PTMS shortly after the Sandpiper PCT application was published and the failure by Judson to search for Sandpiper as an assignee or to search foreign databases. But Akamai did disclose references which Limelight later argued to the jury either anticipated claims in the '703 patent or, when combined, rendered those claims obvious. In addition, it disclosed the Amir paper and explained that the paper could be prior art notwithstanding its apparent date of publication. The Amir paper described the system on which the Peterson presentation was based, a reference heavily relied on by Limelight to invalidate the '703 patent. Thus, I conclude that Limelight has failed to prove by clear and convincing evidence that the Inventors intended to deceive the PTO or that Judson was deliberately indifferent to notice of material information during the pendency of the '703 application. Cf. Brasseler, U.S.A. I., L.P. v. Stryker Sales Corp., 267 F.3d 1370, 1383 (Fed.Cir.2001) (finding attorneys willfully ignored notice of a potentially invalidating event in an conscious effort to avoid complying with their duty to disclose). Limelight has not sustained its burden of proof on its charge of inequitable conduct. B. Limelight’s Defenses of Laches and Equitable Estoppel 1. Legal Standard a. Laches To prevail on its laches defense, Limelight must prove by a preponderance of the evidence that: (1) “the plaintiff delayed filing suit for an unreasonable and inexcusable length of time from the time he knew or reasonably should have known of his claim against the defendant;” and (2) “the delay operated to the prejudice or injury of the defendant.” AC. Aukerman Co. v. R.L. Chaides Constr. Co., 960 F.2d 1020, 1032 (Fed.Cir.1992) (en banc). The laches period begins to run when the patentee has actual or constructive knowledge of the infringer’s activity. Id. A successful laches defense “bars relief on a patentee’s claim only with respect to damages accrued prior to suit.” Id. at 1041. A presumption of laches exists where a patent holder delays more than six years before filing suit. Id. at 1035. Here, Limelight alleges only a five-year delay between Akamai learning of Limelight’s CDN in 2001 and its filing of this lawsuit. Therefore, there is no presumption of laches, and “unreasonable delay and prejudice [ ] must be proved and judged on the totality of the evidence presented.” Id. at 1038. b. Equitable Estoppel To show equitable estoppel, Limelight must prove: (1) that Akamai communicated by statements or conduct that it did not intend to press an infringement claim against Limelight; (2) that Limelight substantially relied on this misleading conduct, i.e. it was lulled into a false sense of security in its actions going forward; and (3) that it would be materially prejudiced if Akamai is allowed to proceed. A.C. Aukerman Co., 960 F.2d at 1041. The inferences Limelight derived from Akamai’s conduct must be reasonable. Id. at 1043. “[S]ilence alone will not create an estoppel unless there was a clear duty to speak” or the silence reinforces a plaintiffs acquiescence to a defendant’s conduct. Id. Unlike laches, equitable estoppel does not require an unreasonable passage of time prior to filing suit. Id. at 1041. “Where equitable estoppel is established, all relief on a claim may be barred.” Id. The Federal Circuit has “adopted the preponderance of evidence standard in connection with the proof of equitable estoppel factors, absent special circumstances, such as fraud or intentional misconduct.” Id. at 1046. 2. Factual Background Michael Gordon (“Gordon”), one of the founders of Limelight, testified that Limelight was founded in June 2001 and began marketing its content delivery service in November of that year. Limelight grew and added customers and equipment over the next several years. Late in the first quarter of 2004, officials from Akamai and Limelight met to discuss the possible acquisition of Limelight by Akamai. Over the course of approximately the next six months, Gordon provided Akamai with information on Limelight’s financial results, technology and content delivery architecture. At a meeting in June 2004, Gordon, along with Limelight’s CEO and its Chief Technical Officer, met with a group of Akamai employees, including several technical people. At that meeting, Limelight explained that its network did not choose a best server, rather it used Internet routing techniques to route a user’s request to a particular group of servers and assigned a particular server to fill the request on a round-robin basis. Gordon understood that Akamai viewed the infrastructure and architectures of Limelight’s network as very different from its own. This understanding is confirmed by a summary Akamai prepared during the 2004 negotiations, which described Limelight as “tak[ing] a very different approach to its network architecture than Akamai.” (DX1146, AKL064050.) Indeed, according to Gordon, Akamai reached the conclusion that, after an acquisition, the approach that “Akamai would pursue would be to migrate Limelight’s customers off of Limelight’s architecture and onto Akamai’s and then decommission Limelight’s network.” (Trial Tr. Day 1, 124:11-15, Nov. 12, 2008.) Ultimately, Akamai decided not to make an offer for Limelight. In a late October 2004 email to another of the founders of Limelight, Robert Wood (“Wood”), the Vice President of Corporate Development for Akamai, concluded the discussions with: I ... want to congratulate you on the great business that you and your team have built. I really enjoyed getting to know you and Mike [Gordon] and hope our paths cross again in the future. My understanding from the last conversation with Broadview is that you guys are going to receive tremendous value for the business and I am glad to hear it. (DX1072.) Gordon testified that, although he had general discussions with Wood about the Speedera lawsuit, no one at Akamai ever indicated that Limelight’s CDN infringed any Akamai patents. During and after the 2004 negotiations, Limelight continued to add customers, purchase equipment and add capacity to its network. Gordon testified that Limelight invested about $10 million in capital equipment in 2005 alone. It also added three new United States locations for its servers and began building points of presence in several European cities. Limelight purchased equipment at an increasing rate in 2006, at least doubling its purchases in the six months after the lawsuit was filed compared to the prior six months. In April 2005, Limelight began implementation of a new architecture for its CDN which did not allocate servers on a round-robin basis; rather, it used software that maintained a list of information concerning the “health” of the available servers to select an appropriate server. In early 2006, the parties renewed acquisition discussions, and this time they progressed to an offer by Akamai to acquire Limelight. However, Limelight decided to stay independent and find alternate funding. On June 22, 2006, it rejected Akamai’s final offer, and the parties wished each other well. The following day, Akamai filed this lawsuit charging Limelight with infringing its patents. Gordon testified without contradiction that, prior to notifying him of the lawsuit, Akamai never suggested that Limelight infringed any of its patents or that it had considered suing Limelight. Leighton testified that Akamai began to investigate the possibility that Limelight was infringing its patents in mid-2005 because Limelight was starting to be a serious competitive threat and because the Speedera litigation had been resolved. The investigation concluded about the time the parties renewed their acquisition discussions. While the negotiations were ongoing, Akamai refrained from instituting any legal actions, but Limelight’s disinclination to be bought removed such restraints. On cross-examination, however, Leighton admitted that Akamai viewed Limelight as one of its competitors much earlier than 2005, a view confirmed by an April 2002 Akamai confidential document titled “How To Beat LimeLightNetworks.” (DX1221.) In that report, Akamai recommended that its sales force “[position LimeLight as a start up — just like the other 25 or so that are out there.” (Id. at AKL124384.) In addition, an October 2003 internal Akamai email describes Limelight as “a key competitor in several accounts.” (DX1212.) Akamai clearly recognized Limelight as a potentially serious competitor as early as 2002 and, in its memo, considered how to beat Limelight, not the “other 25 or so” content delivery companies. (DX1221.) In addition, by April 2002 Akamai was aware that Limelight had “snagged one of its notable clients, MusicMatch.com” and was pricing its services aggressively against Akamai’s FreeFlow service. (Id.) However, I find no evidence that Akamai investigated Limelight’s technology in the context of patent infringement prior to mid-2005. Wood participated in both the 2004 and the 2004 acquisition discussion, and I credit his testimony that he was unaware of any investigation by Akamai into the question of patent infringement during the earlier negotiations. In addition, there is no evidence that Limelight’s round-robin CDN implementation infringed any Akamai patent. While Akamai did include this implementation in its initial infringement contentions, it ultimately dropped it from the lawsuit, and the jury awarded damages only for Limelight’s use of the architecture introduced in April 2005. 3. Discussion a. Laches Limelight argues that Akamai’s delay of five years in filing this lawsuit prejudiced it because, had it known that Akamai believed Limelight’s technology infringed its patents, Limelight “would likely not have focused solely on expanding its CDN business but would have also developed and expanded other types of business such as transit and hosting businesses.” (Docket # 353, 7.) Limelight also complains about evidentiary disadvantages, including witnesses’ loss of memory visited upon it as a result of the delay. According to Limelight, since Akamai viewed it as a competitor in the content delivery field, Akamai had a duty to investigate whether Limelight infringed any of its patents and cannot avoid a finding of laches by willful ignorance. Therefore, Limelight argues, Akamai’s infringement damages should be limited to damages accruing after it filed suit in 2006. Akamai responds that it did not learn that Limelight might