The part of a Klingon trial before the High Council in which evidence is presented, during which the accused's challenger is supported by a second known as the cha'DIch.
The Mek'ba is the stage of a Klingon legal challenge at which evidence is laid before the High Council. A challenger may not fight while the challenge stands, so he names a cha'DIch, a second who defends him and may speak for him.
Both terms come from Sins of the Father in 2366. Worf's late father Mogh is accused of betraying the Khitomer outpost to the Romulans, and Worf goes to the homeworld to contest the charge, knowing that failure means his own execution. His brother Kurn serves as cha'DIch until he is stabbed by assassins, and Worf then asks Jean-Luc Picard to take the role.
Picard's search for the truth leads to the old nurse Kahlest and to the discovery that the real traitor was Ja'rod, father of Duras. To prevent civil war, Worf accepts discommendation instead.