A patent’s term defines the length of time the patent holder may exclude others from using the invention. For pharmaceutical inventions, which usually undergo a lengthy FDA approval process before any drug can be sold, the most valuable portion of patent term is at the end of the patent’s life, after FDA approval. Patent owners understandably want to maximize their patent’s life and competitors want the patent to expire as soon as possible.

One way for competitors to try to shorten a patent’s term during litigation is to allege that an asserted patent is invalid because of obviousness-type double patenting (OTDP). OTDP is a judicial doctrine that prevents a patentee from obtaining multiple patents with claims that are obvious variants of one another, but have different expiration dates. The doctrine prohibits an inventor from extending her right to exclude others from using the invention with claims in a later-expiring patent that are not patentably distinct from claims in her earlier-expiring patent. Faced with such a challenge, the patentee can disclaim the term after the earlier expiration date (with a terminal disclaimer). The end result of a challenge will be to limit the term to the earlier expiration date.