Non-infringement/invalidity opinions help protect against claims of willful infringement. You may be a willful infringer if you have knowledge of an existing patent during alleged infringing activity. Knowledge of an existing patent can arise in any number of ways, but most commonly when an alleged infringer receives a cease and desist letter from a patent holder. Willful infringers are subject to increased damages during litigation (triple damages) as punishment for their disregard of a known patent.
A legal opinion from a competent, out-of-house patent attorney of non-infringement or invalidity is a significant factor considered by the courts in determining whether willful infringement occurred. Obtaining a competent legal opinion typically protects against claims of willful infringement even if the court ultimately finds that infringement did occur.