<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>
when did jack mccoy join law and order
the season - five premiere episode `` Second Opinion ''