N.H. Rev. Stat. Ann. § 622-C:1

Whenever a treaty is in force between the United States and a foreign country providing for the transfer or exchange of convicted offenders to the country of which they are citizens or nationals, the governor may, on behalf of the state and subject to the terms of the treaty, authorize the commissioner of corrections to consent to the transfer or exchange of offenders and to take any other action necessary to implement the participation of this state in the treaty.