In its recent decision in Commil USA, LLC v. Cisco Systems, the U.S. Supreme Court held that a defendant’s good faith belief that the patent at issue was invalid is not a defense to a claim of induced infringement under 35 U.S.C. §271(b). The Court explained that the defendant’s belief in the patent’s invalidity cannot serve to negate the intent requirement of §271(b), because the act of infringement is a separate issue from that of the validity of the patent.

The Court explained that this reasoning is reflected in the way the civil law approaches other issues, such as tortious interference with a contract. If a contract is invalid, that would be a defense to tortious interference, but the interferer’s mere belief of invalidity would be irrelevant. Thus, the good faith belief alone, without proof of invalidity, will not save an alleged infringer.

If a business wants to use something that’s patented and thinks it can avoid liability by having a good faith belief that the patent is invalid, the business could still be held liable for significant damages.