The U.S. Court of Appeals for the Federal Circuit has affirmed a Texas district court ruling in favor of Google Inc., Microsoft Corp., and Yahoo Inc. that invalidated a patent related to paid advertisement services.

Ohio-based Paid Search Engine Tools sued the defendants in the Eastern District of Texas, alleging their paid advertisement services infringed one of its patents. District Judge David Folsom granted the defendants’ motion for summary judgment, saying the patent was not valid based on prior art. In its opinion issued Monday, the Federal Circuit agreed without elaborating.