New York Consolidated Laws, Criminal Procedure Law - CPL § 360.30 Trial jury;  peremptory challenge of an individaul  1] juror

1. A peremptory challenge is an objection to a prospective juror for which no reason need be assigned.  Upon any peremptory challenge, the court must exclude the person challenged from service.

2. Each party must be allowed three peremptory challenges.  When two or more defendants are tried jointly, such challenges are not multiplied by the number of defendants, but such defendants are to be treated as a single party.  In any such case, a peremptory challenge by one or more defendants must be allowed if a majority of the defendants join in such challenge, or if there is a tie when there is an even number of defendants.  Otherwise, it must be disallowed.