<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> <P> Waterston's performance as McCoy on the New York - based series was so popular that it resulted in him being declared a "Living Landmark" by the New York Landmarks Conservancy, along with fellow longtime series cast member Jerry Orbach (who portrayed the popular police detective Lennie Briscoe for 12 years). </P> <P> Jack McCoy brings 24 years of experience with him as he is appointed executive assistant district attorney by Adam Schiff (Steven Hill) in the season five premiere episode "Second Opinion". He quickly establishes himself as a more unconventional, ruthless litigator than his predecessor, Ben Stone (Michael Moriarty). He often bends--and sometimes breaks--trial rules to get convictions, finds tenuous rationales for charging defendants with crimes when the original charges fail to stick, and charges innocent people to frighten them into testifying against others . McCoy is found in contempt of court 80 times for such behavior, and his tactics occasionally incur negative publicity for the DA's office . His underlying motivation, however, is not, he maintains, corruption, but a sincere desire to see justice done . To that end, McCoy has gone after defendants accused of perverting the justice system to arrange wrongful convictions with just as much determination as his more mundane cases . Such aggressive actions in the courts have earned him the nickname "Hang' em High McCoy". He has subsequently developed a reputation with both colleagues and rival attorneys, once being referred to as "the top of the legal food chain" by a rival attorney during a trial . </P> <P> Following the 17th season (2006--2007), Jack McCoy was appointed interim district attorney, taking over from Arthur Branch (Fred Thompson). McCoy's appearance on Law & Order: Special Victims Unit on the November 13, 2007, episode "Blinded", marked his first appearance in the Law & Order universe as district attorney . The replacement for his former position is Michael Cutter (Linus Roache), a prosecutor with a penchant for recklessness not unlike McCoy's own in his younger days . This occasionally presents political difficulties for the new district attorney . More than once, McCoy berates Cutter for reckless conduct, in the same manner as he was berated by district attorneys when he was executive assistant district attorney . </P>

What season did mccoy join law and order