Complex sentence: Sullivan became a partner and was actively engaged in the general practice of law with that firm until August 1980, when his partner, William C. Gardner, was appointed as an Associate Judge of the Superior Court of the District of Columbia.
Split into simpler sentences: Sullivan became a partner and was actively engaged in the general practice of law with that firm. In August 1980, his partner, William C. Gardner, was appointed as an Associate Judge of the Superior Court of the District of Columbia.