Va. Code § 15.2-1726
Any locality may, in its discretion, enter into a reciprocal agreement with any other locality, any agency of the federal government exercising police powers, the police of any public institution of higher education in the Commonwealth appointed pursuant to subsection B of § 23.1-812, the Division of Capitol Police, any private police department certified by the Department of Criminal Justice Services, or any combination of the foregoing, for such periods and under such conditions as the contracting parties deem advisable, for cooperation in the furnishing of police services. Such agreements may include designation of mutually agreed-upon boundary lines between contiguous localities for purposes of organizing 911 dispatch and response and clarifying issues related to coverage under workers' compensation and risk management laws. Such agreements may also include provisions allowing for the loan of unmarked police vehicles. Such localities also may enter into an agreement for the cooperation in the furnishing of police services with the Department of State Police. The governing body of any locality also may, in its discretion, enter into a reciprocal agreement with any other locality, or combination thereof, for the consolidation of police departments or divisions or departments thereof. Subject to the conditions of the agreement, all police officers, officers, agents and other employees of such consolidated or cooperating police departments shall have the same powers, rights, benefits, privileges and immunities in every jurisdiction subscribing to such agreement, including the authority to make arrests in every such jurisdiction subscribing to the agreement; however, no police officer of any locality shall have authority to enforce federal laws unless specifically empowered to do so by statute, and no federal law-enforcement officer shall have authority to enforce the laws of the Commonwealth unless specifically empowered to do so by statute.
The governing body of a county also may enter into a tripartite contract with the governing body of any town, one or more, in such county and the sheriff for such county for the purpose of having the sheriff furnish law-enforcement services in the town. The contract shall be structured as a service contract and may have such other terms and conditions as the contracting parties deem advisable. The sheriff and any deputy sheriff serving as a town law-enforcement officer shall have authority to enforce such town's ordinances. Likewise, subject to the conditions of the contract, the sheriff and deputy sheriffs while serving as a town's law-enforcement officers shall have the same powers, rights, benefits, privileges and immunities as those of regular town police officers. The sheriff under any such contract shall be the town's chief of police.
Va. Code § 15.2-1726