MEMORANDUM OPINION AND ORDER

RODNEY GILSTRAP, District Judge.

Before the Court is Defendants' Opposed Motion for Leave to Supplement Invalidity Contentions, filed November 27, 2012.1 The Court having considered the same finds that the motion should be DENIED.

I. Applicable Law

A party's invalidity contentions are deemed to be the party's final invalidity contentions unless amendment or supplementation is permitted by the Local Patent Rules. P.R. 3-6. In limited circumstances, amendment of invalidity contentions is permitted as of right. P.R. 3-6(a). Otherwise, amendment "may be made only by order of the Court, which shall be entered only upon a showing of good cause." P.R. 3-6(b). When determining whether a party has demonstrated good cause, the Court considers: (1) the explanation for the party's failure to meet the deadline; (2) the importance of the amendment; (3) potential prejudice from allowing the amendment; and (4) the availability of a continuance to cure such prejudice. S & W Enters., L.L.C. v. SouthTrust Bank of Alabama, NA, 315 F.3d 533, 536 (5th Cir. 2003).

II. Discussion

Defendants served their invalidity contentions on August 17, 2012. By the present motion, Defendants seek leave pursuant to Patent Rule 3-6(b) to supplement their invalidity contentions to include 36 additional prior art references describing the following five prior art systems: (1) EAAsy Sabre; (2) Prodigy; (3) America On Line ("AOL"); (4) CompuServe; and

(5) Delphi (collectively "the Supplemental References"). According to Defendants, their "first inkling" of the relevance of the Supplemental References came on September 5, 2012, when Defendants' counsel received an email from co-counsel stating that "he had gone through some old boxes of books while cleaning out his garage and came across [an early AOL User Guide]." (Dkt. No. 353 at 5, Ex. 1 ¶ 4.) Defendants thereafter searched for earlier versions of the AOL User Guide, as well as additional similar references relating to online Internet service providers. On November 12, 2012, Defendants disclosed the Supplemental References to Plaintiff GeoTag, Inc. ("GeoTag").

The Court is not persuaded that Defendants have acted diligently in discovering such Supplemental References. The Defendants should have, at the least, timely uncovered the AOL User Guide that triggered Defendants' search into the Supplemental References because it had been in the possession of Defendants' counsel. While Defendants argue that "it is often more difficult to identify web-based prior art" (Dkt. No. 353 at 8), the Supplemental References here are not obscure internet references but include what might well be described as the largest and most popular internet systems of the 1980s and 1990s. Indeed, Defendants did not appear to encounter any difficulty in finding and attaining the references once the discovery of the AOL User Guide prompted the search. (See Dkt. No. 353 Ex. 1 ¶¶ 4-7.) Moreover, the patent-in-suit itself discloses both AOL and Compuserve, and Defendants' original invalidity contentions cited a system that explicitly ran on Prodigy. Ultimately, Defendants' only explanation for its untimely invalidity contentions is that counsel happened upon a reference while cleaning out his garage. Such happenstance discovery in these circumstances does not demonstrate the diligence necessary to support the late supplementation now requested. In the Court's view, to hold otherwise would render "the explanation for the party's failure to meet the deadline" a non-factor.

III. Conclusion

Based on the foregoing reasons, the Court finds that Defendants' Opposed Motion for Leave to Supplement Invalidity Contentions should be and is hereby DENIED.