Section 21

In like manner a certificate purporting to be under the hand of an analyst shall, on production thereof by the defendant be sufficient evidence of the facts stated therein unless the prosecutor requires that the analyst be called as a witness.

A copy of such last-mentioned certificate shall be sent to the prosecutor at least three clear days before the day fixed for the hearing of the summons, and if it is not so sent the court may adjourn the hearing on such terms as it may think proper.

Court may order independent analysis