A recent U.S. Court of Appeals for the Federal Circuit decision puts the patent bar on notice that vague claims of another lawyer’s intent to mislead or withhold data from the U.S. Patent and Trademark Office will no longer fly.

The precedent-setting Tuesday ruling in Exergen Corp. v. Wal-Mart Stores Inc. makes it harder for patent lawyers to prove that another attorney intentionally deceived the PTO when presenting a patent application. Lawyers defending patent infringement cases frequently accuse the other side of such misconduct — referred to as inequitable misconduct — which can disqualify a patent or some of its claims. Attorneys say misconduct accusations are so frequent and frivolous that they’re significantly driving up the cost of patent litigation.