Patent Invalidity as a Defense

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A lawsuit for patent infringement almost always becomes two separate battles—one in which the plaintiff claims damage from infringement, and the other in which the defendant attempts to terminate the patent rights by proving the patent is invalid. For example, the Polaroid company sued Kodak for infringement of ten instant photography patents. The court determined that Kodak infringed seven Polaroid patents but that the other three Polaroid patents were invalid.

To prove that a patent is invalid, the defendant must attack the patent on the basis of lack of novelty or nonobviousness—that is, show prior art that anticipates or renders the patent’s claims obvious or prove that sales or disclosure of the patented invention occurred more than one year prior to filing the patent application.

Example: A company was sued for infringement of a patented device for displaying computer text on a television monitor. The company defended itself by proving that more than one year prior to filing its patent application the company filing the suit had submitted a proposal for sale of the invention. On that basis, the patent was invalidated and there was no infringement. (RCA Corporation v. Data General Corporation, 887 F.2d 1056 (Fed. Cir. 1989).)

In 2011, the Supreme Court refused to alter the standard for invalidating a patent in a battle between tech companies. Microsoft was sued for patent infringement by i4i, a Canadian company over an XML feature of Microsoft’s Word software. At trial, Microsoft argued that i4i failed to disclose a prior invention that might have invalidated the application (a principle known as the 'one-year rule'). The jury was instructed that the patent could only be invalidated if there was "clear and convincing" evidence of invalidity. (Microsoft Corp. v. i4i Limited Partnership, __ U.S. __ (2010)).

Invalidity Under the America Invents Act

Note, the one-year rules regarding prior art discussed above will terminate in March 2013 when the U.S. switches to a first-to-file system. Patents filed 18 months after enactment of the America Invents Act (Enacted September 16, 2011) will be subject to new first-to-file and prior art rules, effectively ending centuries of first-to-invent rules. In short, prior art will generally refer to anything that existed prior to filing (not one year preceding the filing). For more information, check the entry for the America Invents Act.