Ya'nora kor was a Klingon rite that could be exercised by the gin'tak of a Great House. The ya'nora kor allowed the gin'tak to question the fitness of the leader of a family to make decisions, specifically those that had a direct impact on the standing of the House or its future.
In 2370, K'mtar threatened to invoke ya'nora kor to take Alexander away from Worf and send him to the Klingon training academy on Ogat. This was due to K'mtar’s belief that Alexander had suffered for his lack of tutelage in combat skills and Klingon ways. (TNG: "Firstborn")
In a deleted scene, Deanna Troi points out that if ya'nora kor were invoked, Worf’s vote would cancel K'mtar’s, and it would fall to Kurn to decide who would get custody of Alexander. [1]