Article 589. ยง 1. A witness or expert who is not a Polish citizen and who, when summoned from abroad, appears voluntarily before the court, cannot be prosecuted or arrested, or put under preliminary detention either by reason of an offence relevant to the criminal proceedings, or of any other offence committed before he crossed the Polish border. The penalty imposed for such offence may not be executed with respect to him.
2. The Court shall have the authority to provide an assurance to a witness or an expert appearing before the Court that he or she will not be prosecuted, detained or subjected to any restriction of personal freedom by the Court in respect of any act or omission that preceded the departure of that person from the requested State.