New York Consolidated Laws, Criminal Procedure Law - CPL § 360.35 Trial jury;  alternate juror

1. Immediately after the last trial juror is sworn, the court may in its discretion direct the selection of either one or two additional jurors to be known as “alternate jurors.”  The alternate jurors must be drawn in the same manner, must have the same qualifications, must be subject to the same examination and challenges for cause and must take the same oath as the regular jurors.  Whether or not a party has used its peremptory challenge in the selection of the trial jury, one peremptory challenge is authorized in the selection of the alternate jurors.

2. The provisions of section 270.35 with respect to alternate jurors are also applicable to a trial jury in a local criminal court.