Section 250.20. Notice of alibi

1.    At  any  time,  not more than twenty days after arraignment, the
  people may serve upon the defendant or his  counsel,  and  file  a  copy
  thereof  with the court, a demand that if the defendant intends to offer
  a trial defense that at the time of the commission of the crime  charged
  he was at some place or places other than the scene of the crime, and to
  call witnesses in support of such defense, he must, within eight days of
  service  of  such demand, serve upon the people, and file a copy thereof
  with the court, a "notice of alibi," reciting (a) the  place  or  places
  where the defendant claims to have been at the time in question, and (b)
  the  names,  the residential addresses, the places of employment and the
  addresses thereof of every such alibi witness upon whom  he  intends  to
  rely.  For good cause shown, the court may extend the period for service
  of the notice.
    2.   Within a reasonable time after receipt of the defendant's witness
  list but not later than ten days before trial,  the  people  must  serve
  upon  the  defendant  or  his  counsel, and file a copy thereof with the
  court, a list of the witnesses the people propose to offer  in  rebuttal
  to  discredit  the  defendant's  alibi  at  the  trial together with the
  residential addresses,  the  places  of  employment  and  the  addresses
  thereof  of  any  such  rebuttal witnesses.   A witness who will testify
  that the defendant was at the scene of the crime is not  such  an  alibi
  rebuttal witness.  For good cause shown, the court may extend the period
  for service of the list of witnesses by the people.
    3.   If at the trial the defendant calls such an alibi witness without
  having served the demanded notice of alibi, or if having served  such  a
  notice  he  calls a witness not specified therein, the court may exclude
  any testimony of such witness relating to the alibi defense.  The  court
  may  in  its  discretion receive such testimony, but before doing so, it
  must, upon application of the people, grant an adjournment not in excess
  of three days.
    4.  Similarly, if the people fail to serve and  file  a  list  of  any
  rebuttal  witnesses,  the  provisions of subdivision three, above, shall
  reciprocally apply.
    5.  Both the defendant and the people shall be under a continuing duty
  to promptly disclose the names and  addresses  of  additional  witnesses
  which  come  to the attention of either party subsequent to filing their
  witness lists as provided in this section.