Maryland Code, Criminal Procedure § 2-105

(1) the county executive and county council of a charter county with a county executive;

(2) the county council of a charter county with no county executive;

(3) the board of county commissioners of a county; or

(4) the mayor and council, by whatever name known, of a municipal corporation.

(c)(1) The acts done by the police officers or other officers, agents, or employees of a county or municipal corporation under the authority of subsection (b) of this section and the expenditures made by the county or municipal corporation are considered to be for a public and governmental purpose.

(2) When a county or municipal corporation is acting through its police officers or other officers, agents, or employees for a public or governmental purpose beyond its boundaries under this section or other lawful authority, the county or municipal corporation has the same immunities from liability that the county or municipal corporation has when acting through its police officers or other officers, agents, or employees for a public or governmental purpose within its boundaries.

(3) When the police officers or other officers, agents, or employees of a county or municipal corporation are acting beyond the boundaries of the county or municipal corporation within the State under this section or other lawful authority, the police officers and other officers, agents, and employees of the county or municipal corporation have the same immunity from liability described in § 5-612 of the Courts Article and exemptions from laws, ordinances, and regulations, and the same pension, relief, disability, workers' compensation, and other benefits as those persons have while performing their duties within the boundaries of the county or municipal corporation.

(e)(1) The governing body of a county or municipal corporation or the Maryland-National Capital Park and Planning Commission may make a reciprocal agreement for the period that it considers advisable with the District of Columbia or a county, municipal corporation, or the Maryland-National Capital Park and Planning Commission, within or outside the State, and establish and carry out a plan to provide mutual aid by providing its police officers and other officers, employees, and agents, together with all necessary equipment as provided in subsection (b) of this section.

(2) A county, municipal corporation, or the Maryland-National Capital Park and Planning Commission may not make a reciprocal agreement unless the agreement provides that each party shall:

(g)(1) The police officers and other officers, agents, and employees coming from one county or municipal corporation to another within the State under a reciprocal agreement under this section may enforce the laws of the State to the same extent as authorized law enforcement officers of the receiving county or municipal corporation.

(2) The police officers and other officers, agents, and employees coming into the State under a reciprocal agreement under this section may enforce the laws of the State to the same extent as authorized law enforcement officers of a county or municipal corporation in the State.