N.H. Rev. Stat. § 614:1
Except as provided in RSA 614:1-a, any member of a duly organized state, county, or municipal peace unit of another state of the United States who enters this state in fresh pursuit, and continues within this state in such fresh pursuit, of a person in order to arrest him or her on the ground that he or she is believed to have committed a felony or to have driven a motor vehicle or operated a boat while under the influence of intoxicating liquor or a controlled drug in such other state, shall have the same authority to arrest and hold such person in custody as has any member of any duly organized state, county, or municipal peace unit of this state to arrest and hold in custody a person on the ground that he or she is believed to have committed a felony or to have driven a motor vehicle or operated a boat in this state while under the influence of intoxicating liquor or a controlled drug.
RSA 614:1
1937, 54:1. RL 439:1. RSA 614:1. 1986, 193:5, eff. Aug. 2, 1986. 2003, 252:4, eff. July 14, 2003.