It's easier than you might think to bargain away the right to challenge patent validity at the U.S. Patent and Trademark Office.

The U.S. Court of Appeals for the Federal Circuit on Thursday upheld San Francisco U.S. Magistrate Judge Elizabeth Laporte's order last year compelling MerchSource LLC, also known as Sharper Image, to withdraw its administrative challenges to three patents on virtual reality headsets.

Dodocase VR had licensed the patents to MerchSource, with the two agreeing that “any dispute arising out of or under this agreement” would be resolved in California courts. A year later MerchSource stopped paying royalties and Dodocase sued for infringement.