Idaho Code § 37-2508

In all prosecutions arising under this chapter the certificate of any chemist from a qualified testing laboratory as approved by the department of agriculture, when duly sworn to by such officer shall be prima facie evidence of the fact or facts therein certified, or in case it is necessary for such chemist to appear as a witness in court, the judge of the district court wherein such trial shall be held, shall issue a subpoena for his attendance at the trial and it shall be the duty of such chemist to obey such subpoena, and all his actual and necessary expenses shall be paid by the county wherein such trial is held in the same manner that county officers are paid and, in case of conviction, shall be charged to the defendant as part of the costs of prosecution.