The number of whistleblower suits against companies that mark their products with expired patents exploded over the last year-and-a-half. But the boom appears to be over.

In recent years, one of the reasons for the ballooning cost of patent litigation is defense claims that patent holders deceived the Patent and Trademark Office, and so their patents are invalid because of inequitable conduct. On Tuesday the appeals court said enough is enough and raised the bar for misconduct allegations.