Maryland Courts and Judicial Proceedings Section 9-106
(a)   The spouse of a person on trial for a crime may not be compelled to testify as an adverse witness unless the charge involves:
(1)   The abuse of a child under 18; or
(2)   Assault in any degree in which the spouse is a victim if:
(i)   The person on trial was previously charged with assault in any degree or assault and battery of the spouse;
(ii)   The spouse was sworn to testify at the previous trial; and
(iii)   The spouse refused to testify at the previous trial on the basis of the provisions of this section.
(b)   (1)   If the spouse of a person on trial for assault in any degree in which the spouse was a victim is sworn to testify at the trial and refuses to testify on the basis of the provisions of this section, the clerk of the court shall make and maintain a record of that refusal, including the name of the spouse refusing to testify.
(2)   When an expungement order is presented to the clerk of the court in a case involving a charge of assault in any degree, the clerk shall check the record to determine whether the defendant's spouse refused to testify on the basis of the provisions of this section.
(3)   If the record shows such refusal, the clerk shall make and maintain a separate record of the refusal, including the defendant's name, the spouse's name, the case file number, a copy of the charging document, and the date of the trial in which the spouse refused to testify.
(4)   The separate record specified under paragraph (3) of this subsection:
(i)   Is not subject to expungement under Title 10, Subtitle 1 of the Criminal Procedure Article; and
(ii)   Shall be available only to the court, a State's Attorney's office, and an attorney for the defendant.