Examiners at the U.S. Patent & Trademark Office have used Wikipedia to help determine a patent application’s validity on everything from from car parts to chip designs. But on Aug. 15, reports Business Week’s Lorraine Woellert, the PTO told its examiners that they could no longer use the controversial online encyclopedia as an accepted source of information.

Said Patents Commisioner John Doll: “The problem with Wikipedia is that it’s constantly changing.” Doll says the agency used Wikipedia entries as background and not as the basis for deciding on an application. A PTO spokesperson attributed inquiries from Business Week for the shift in policy.

“I’ve been complaining about this for years,” says Greg Aharonian, a longtime agency muckraker who writes a patent newsletter. “From a legal point of view, a Wiki citation is toilet paper.”