Idaho Code § 50-209: Powers of policemen.

The policemen of every city, should any be appointed, shall have power to arrest all offenders against the law of the state, or of the city, by day or by night, in the same manner as the sheriff or constable. Whenever such policemen shall be in fresh pursuit of any offender against any law of the state, including traffic infractions, or of the city and the offense has been committed within the corporate limits of such city, such policemen, while in such fresh pursuit may go beyond the corporate or geographical limits of such city subject to the provisions of chapter 7, title 19, Idaho Code, for the purpose of making such arrest or citation.