This could get interesting. HTC has filed its answer to Apple's complaint [PDFs] against them for patent infringement, with affirmative defenses and counterclaims.
The case, Apple Inc. v. High Tech Computer Corp. et al, is now before Judge Gregory M. Sleet, docket number: 1:10-cv-00544-GMS, in the US District Court in Delaware. The et al means there are others as defendants, and the full caption is Apple Inc. and NeXt Software, Inc. v. High Tech Computer Corp., a/k/aHTC Corp., HTC (B.V.I.) Corp., HTCAmerica, Inc., and Exedea, Inc. The defendants are asking to move the case from Delaware, where Apple filed, to Northern California. I don't know about you, but I'd rather be in any state *but* Delaware, after watching SCO's bankruptcy there.
HTC denies infringing the patents, of course, but they also say as a first affirmative defense that four of the patents are invalid for "failure to comply with one or more of the conditions for patentability set forth in Title 35 of the United States Code, including, but not limited to, utility, novelty, non-obviousness, enablement, written description and definiteness in accordance with 35 U.S.C. §§ 101, 102, 103, 112, and/or 116, or are invalid pursuant to the judicial doctrine barring double-patenting". HTC also claims prior art, marking, laches and marking defenses, and it says it has license agreements with third party suppliers to do what they do the things Apple is suing them over. It asks the court to declare the patents invalid. Here's a recent case highlighted on EFF's site where some of those types of defenses worked perfectly.
You know how in the movies when two guys get into a fight on the street, another guy will run into a bar and yell, Fight! and everyone runs outside to watch? I feel like that guy reading this filing, because I see HTC intends to fight back.

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