Artikel 37

1. A witness, expert or other person who, at the request of the requesting State Party, consents to give evidence in a proceeding or to assist in an investigation, prosecution or judicial proceeding in the territory of the requesting State Party shall not be prosecuted, detained, punished or subjected to any other restriction of personal liberty in that territory in respect of acts, omissions or convictions prior to departure from the territory of the requested State Party.
2. The safe conduct provided for in paragraph 1 shall cease when the witness, expert or other person:
a) Having had, for a period of 15 consecutive days or for any period agreed upon by the States Parties concerned from the date on which the person has been officially informed that the person's presence is no longer required by the judicial authorities of the requesting State Party, an opportunity of leaving, has nevertheless remained voluntarily in the territory of the requesting State Party; or
b) Having left the territory of the requesting State Party, has returned of the person's own free will.