A federal judge abused her discretion in denying attorney fees to a patent litigant after finding “an egregious pattern of misconduct” by the other side, a federal appeals court has ruled.

The U.S. Court of Appeals for the Federal Circuit sent Oplus Technologies v. Vizio back to the Central District of California and told Senior Judge Mariana Pfaelzer to reconsider whether to award fees.

“Given that the district court found counsel's behavior 'inappropriate,' 'unprofessional,' 'vexatious' and 'harassing,' it is difficult to imagine how Vizio Inc. had not incurred additional expenses defending against such filings,” Judge Kimberly Moore wrote in Friday's ruling.