The original series from 1990 for a long while didn't have a female recurring character (assistant DA or Police Officer or Police Chief). It as all Male for a while.
Carolyn McCormick, Anita Van Buren and Jill Hennessy were I think the first women to have a recurring role in the Original Law and Order.
Sam Waterson played the DA for 368 episodes but Hargitay has him beat!