In patent litigation invalidity arguments are formal submissions made by the party asserting invalidity of a patent and stating the bases upon which a patent is to be considered invalid. The arguments arecentral to drafting an effective defense and framing strategic thinking in a case of litigation. Best practices include performing exhaustive research, framing comprehensive claim charts, and adherence to local patent laws. A well-crafted invalidity contention can change the landscape of a legal case by either dismantling the plaintiff's case or by invalidating the patent. There are some key practices followed by experts while structuring an effective invalidity defense.

On being notified to find itself facing a charge of patent infringement, a firm has to immediately begin a diligent investigation of the asserted patent. The earlier it takes this step, the greater are its chances of finding strong and relevant prior art, by virtue of which it can later develop its arguments of law. At this point, it is important to make oneself conversant with the contentious claims, and more importantly with wider claims since they are susceptible to challenge as invalid to a greater extent. It is beneficial to bring to work technical experts early in life and those who are well-versed with the respective industry or technology.

The interpretation of the patent claims forms the foundation of any invalidity assertion. The judges determine the correct construction of each of the claims' terms, and you should do likewise. Having a read through the entire patent covering the background, examples, and description by the inventor of their invention is recommended. The critical read through can unveil statements open to various interpretations or show all else equal to find out that the scope of the claims is tighter than initially thought. Valid arguments for invalidity are founded upon justified interpretations - broad and narrow - so they hold regardless of how a court interprets the claims.

Use Prior Art Strategically

The key element to any invalidity defense is to find and exploit prior art publicly known papers or technology demonstrating by illustration that the claimed invention was known or obvious at the date of filing. Prior art can consist of previously issued patents, technical articles, standards documents, user manuals for products, or previous versions of a product.

Do not mindlessly search for keyword searches when you're looking for prior art. Try out some different tools based on classification codes, citation chains, and semantic search sites. Often the best prior art is set out with a different lexicon than is being used in the patent you are examining. Note also that you can set out different references to make an obviousness case. One file can reveal some aspect of the invention and another can reveal the rest with a short narrative to set out why one would combine them.

It is possible to include all possible arguments in an invalidity argument but occasionally less is better. Make the strongest and simplest arguments first. Does there exist one prior piece of prior art disclosing all elements of a claim? That is ideal for an anticipation argument. Do there exist two or three references whereby, collectively, they show the same thing? That is a good starting point for obviousness. Stick to those things that can be proved with certain and precise evidence without it or speculative arguments hardly ever get through to the court.

Final Thoughts

Invalidity arguments are a key part of the patent litigation strategy. Executed well, invalidity arguments can potentially invalidate some of strongest claims to a patent. This is never a process to undertake as a checklist; it is time-consuming and laborious and requires a high level of technical and legal expertise. By beginning early, being thoroughly familiar with the claims at a deep technical and prosecutorial level, monitoring high-quality prior art, and working with expert knowledgeable individuals, defendants can fashion a strong case that a patent is not entitled to its desired legal protection. In high-stake patent cases today, an educated invalidity strategy can be a game-changer.

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