SAN JOSE — Quinn Emanuel is in such a tight spot over its apparent mishandling of confidential documents that the firm’s founder, John Quinn, came to its defense at a hearing on Tuesday.

As Apple and Samsung prepare to take their long-running patent spat to a jury once more, Apple accuses lawyers at Quinn Emanuel Urquhart & Sullivan of sharing confidential terms of its licensing agreements with Samsung and is seeking sanctions for the breach. Apple contends Samsung then used the information to gain an upper hand in negotiations with other companies and in disputes before other courts.