Maryland § 2-204

§ 2-204.

    (a)    A police officer without a warrant may arrest a person if:

        (1)    the police officer has probable cause to believe that:

            (i)    the person battered the person’s spouse or another person with whom the person resides;

            (ii)    there is evidence of physical injury; and

            (iii)    unless the person is arrested immediately, the person:

                1.    may not be apprehended;

                2.    may cause physical injury or property damage to another; or

                3.    may tamper with, dispose of, or destroy evidence; and

        (2)    a report to the police was made within 48 hours of the alleged incident.

    (b)    If the police officer has probable cause to believe that mutual battery occurred and arrest is necessary under subsection (a) of this section, the police officer shall consider whether one of the persons acted in self-defense when determining whether to arrest the person whom the police officer believes to be the primary aggressor.