Sam Waterston has brought order in the court. The “Law & Order” regular has agreed to stick with the hit NBC drama, helping to keep the show’s cast unusually stable.

“Law & Order,” where the dressing rooms seemed to have revolving doors for much of the show’s 13-season history, has seen fewer onscreen shuffles in recent years. Waterston, for example, has played assistant D.A. Jack McCoy on the skein since 1994. The most recent addition was Fred Thompson, who joined “L&O” last season as District Attorney Arthur Branch.

No cast changes are in store for the upcoming season, the show’s 14th.

Under the new arrangement, Waterston will stick with “Law & Order” at least through the show’s 2004-05 season, which is when NBC’s current license for the show expires.

Waterston, who’s repped by ICM, has received six Emmy noms through the years, including three for his work on “Law & Order.” He won one for hosting the special “Lost Civilizations” and scored a Golden Globe Award for his work on series “I’ll Fly Away.”

Waterston’s film credits include upcoming release “Le Divorce.”