Mr Slobodan Milosevic has challenged the legality of the UN war crimes tribunal and of his arrest.
It came before he began his response to prosecution charges that he murdered and oppressed non-Serbs in a relentless pursuit of personal power.
Mr Milosevic was given his chance to speak after a two-day presentation of the prosecution's case, but with less than 30 minutes left before a scheduled adjournment, he declined to begin his formal statement.
Instead, he demanded that the trial judges respond to his motions during pre-trial hearings that the court was illegal and that his arrest and transfer to The Hague violated the Serb and Yugoslav constitutions.
"I challenge the legality of this court because it is not established on the basis of law," Mr Milosevic said.
He accused chief prosecutor Carla Del Ponte of already proclaiming his guilt and his sentence by conducting "a parallel legal process" in the media.
Presiding judge Richard May rejected his charges, and said the court had already ruled on its own legality. "Your views on this court are entirely irrelevant," he said.
He then adjourned the day's hearings.
Mr Milosevic (60) faces a total of 66 counts of genocide and other war crimes during a decade of strife in the republics that once made up Yugoslavia.
Mr Milosevic's legal advisers say his he will argue that he is not a war criminal but a leader who sought unity and peace in his country.
PA