Before 1992, the branch existed as the independent Army Legal Corps (ALC).

Many of the functions of the ALS were once carried out by the Judge Advocate General (JAG) whose own origins can be traced back to medieval times.

Following World War I, the growing demand for legal services within the army led in 1923 to the creation of the Military Department of the Office of the Judge Advocate General.

[1] The Directorate of Army Legal Services was formed from the JAG's office on 1 October 1948 and would go on to receive full corps status as the Army Legal Corps on 1 November 1978.

[2] The head of the Army Legal Services Branch is its director.