Patent Validity Opinion Law and Legal Definition

Validity opinion refers to a patent attorney's opinion about the likelihood that a patent or patent claim will be invalidated in light of evidence suggesting obviousness, lack of invention, unenforceability, etc. In the case of a patent infringement, proof of “invalidity” or “unenforceability” is the first line of defense. The first step in determining the validity of a patent is to check whether the patent term has expired or the maintenance fees have not been paid. If the patent is still valid, a request for a “patent validity opinion” is lodged with the company’s patent attorney or law firm. The attorney after analyzing all the materials issues the validity opinion.