Expansion of the “Prior Commercial Use” Affirmative Defense

The 1999 American Inventors Protection Act (AIPA), an earlier attempt at patent-law reform, created a limited “prior commercial use” affirmative defense. This prior commercial use defense protected practitioners of certain types of business methods from certain types of patent-infringement claims. Specifically, the defense applied when a business-method owner elected to maintain his or her business method as a trade secret.

Prior to the passage of the AIPA, an inventor could independently discover the business method in question and obtain patent protection for the business method. Then the inventor could assert his or her patent against the practitioner of the secret business method.

This limited prior commercial use affirmative defense provision in the AIPA was unusual in that it only applied to a certain type field of technology, namely business methods. The AIA expanded this limited prior commercial use affirmative defense, so that it can be applied in other fields.

The defense is a personal defense, which means that another entity can only obtain the defense from a third party through an acquisition of the third party. The statute also includes exceptions for universities and nonprofits.

One potential hazard of asserting this defense is that the statute makes the award of attorney’s fees mandatory if the accused infringer is unsuccessful.

Elimination of the Best-Mode Affirmative Defense

The AIA eliminated the affirmative defense of failure to comply with the best-mode requirement. This means that a patent cannot be invalidated in litigation for failure to disclose the best mode during patent prosecution. Interestingly, applicants are still required to disclose the best mode in the existing patent statute.

Failure to Obtain an Opinion of Counsel

The AIA codified an earlier decision by the Court of Appeals for the Federal Circuit that held that the failure to obtain an opinion of counsel cannot be used as evidence of willful infringement. An accused infringer can still use an opinion of counsel as a basis for a defense to a claim of willful infringement, but the accused infringer can no longer be penalized in litigation for failing to do so.

Virtual Marking

The AIA made changes to the practice of marking one’s products with patent numbers and to the consequences of false marking. Specifically, the AIA created a procedure for “virtual marking” a product by reference to an internet address. The AIA restricted the availability of certain types of statutory damages for false marking to the federal government. Private parties can only receive compensatory damages when they can show competitive injury. The AIA eliminated the ability to obtain damages for false marking merely because a product has been marked with a patent number for a patent that has expired.


The AIA restricted the ability of patent owners to file a single patent infringement lawsuit against multiple, unrelated accused infringers. The enactment of this section of the AIA has actually resulted an increase in the number of patent infringement actions that have been filed.