Va. Code § 15.2-1736
The governing bodies of localities, institutions of higher learning having a police force appointed pursuant to subsection B of § 23.1-812, and institutions of higher education having a private police force, as well as sheriffs, and the Director of the Department of Conservation and Recreation with commissioned conservation officers, or any combination thereof may, by proper resolutions, enter in and become a party to contracts or mutual aid agreements for the use of their joint forces, both regular and auxiliary, their equipment and materials to maintain peace and good order, including providing transportation for such person subject to an emergency custody order pursuant to § 37.2-808 or providing transportation for a person in the temporary detention process pursuant to § 37.2-810. However, no such institution of higher learning shall enter into such agreement with another institution of higher education in a noncontiguous locality without the consent of all localities within which such institutions are located. Any police or other law-enforcement officer, regular or auxiliary, while performing his duty under any such contract or agreement, shall have the same authority in such locality as he has within the locality where he was appointed.
In counties where no police department has been established, the sheriff may, in his discretion, enter into mutual aid agreements as provided by this section.
Va. Code § 15.2-1736