The US Supreme Court ruled Monday that federal agencies are not “persons” who may take advantage of administrative procedures for challenging patents.

The agency in question, the US Postal Service (USPS), attempted to use administrative procedures from the America Invents Act to challenge a patent held by Return Mail, Inc. USPS had originally tried to license a patented process for undeliverable mail, but Return Mail and USPS could not come to an agreement. USPS introduced a new address-change process for handling undeliverable mail in 2006. Return Mail attempted to offer to license USPS their process again and when that failed, sued USPS for patent infringement. USPS invoked the patent review process from the America Invents Act, and Return Mail’s patent was invalidated by the Patent Trial and Appeal Board. The decision was affirmed by the US Court of Appeals for the Federal Circuit.

The court ruled in a 6-3 opinion by Justice Sonia Sotomayor that a federal agency like the USPS is not a person under the America Invents Act. The majority declared that while the definition of person lists out many possible meanings, government was notably left out, which must have been intentional. Justice Stephen Breyer dissented, with Justices Ruth Bader Ginsburg and Elena Kagan, arguing that Congress gave federal agencies every other possible power related to patents, including licensing their own and suing for infringement, and the majority rule creates a sharp contrast to other federally granted patent powers.