Chief Prosecutor Carla Del Ponte steps down in December after guiding the International Criminal Tribunal in prosecutions and investigations involving war crimes in Bosnia and Lebanon, among others.

Del Ponte's successor is reportedly Belgian criminologist Serge Brammertz, a court deputy prosecutor and relative newcomer to its proceedings, The (British) Observer reported Sunday.

The court's entire senior law staff has taken the unprecedented step of contesting the Brammertz appointment with U.N. Secretary-General Ban Ki-Moon, who has the power to fill the post.

The lawyers threaten to quit if Brammertz is promoted past Del Ponte's deputy David Tolbert, who has worked nine years at the tribunal.

"It's the difference between someone who knows the history, understands every case and can deliver a completion strategy," one lawyer told The Observer.