<P> John James McCoy is a fictional character in the television drama Law & Order . He was created by Michael S. Chernuchin and portrayed by Sam Waterston from 1994 until the end of the series in 2010 . He is the second - longest tenured character on the show ( 16 seasons ) , after Lt. Anita Van Buren ( 17 seasons ; portrayed by S. Epatha Merkerson ) . He appeared in 368 episodes of Law & Order , four episodes of Law & Order : Special Victims Unit , two episodes of Law & Order : Trial by Jury , two episodes of Homicide : Life on the Street , and the made - for - TV movie Exiled . </P>
when did jack mccoy join law and order
1994