The case against Beate Zschaepe, 38, who is accused of being part of a far-right killer cell, and four alleged accomplices who face lesser charges, will resume on May 14 at the court in the southern city of Munich, the judge said.
The postponement follows motions by defence lawyers objecting to the trial's chief judge Manfred Goetzl.
They argue among other things that he is biased in insisting that the defence team undergoes security checks on entering the court while prosecutors, police and others are not required to be searched.
The case only came to light in November 2011 after Zschaepe's alleged accomplices, Uwe Mundlos and Uwe Boehnhardt, were found shot dead in an apparent murder-suicide.