L&O has a habit of taking plots that would be bland on any other show, and adding not just plot twists, but unique thematic layers, that make episodes stand out. This one begins innocuously enough, with a dead city worker and perhaps a link to the trial of an Italian mafioso. But it soon morphs into a character piece focused on the fascinating and electric personality of EADA Jack McCoy, played by Sam Waterston - truly one of the most compelling characters ever on American television.
McCoy faces a blast from the past when a friend/rival from law school, played by Ron Leibman in a ferociously brilliant performance, shows up defending the mafioso; the defendant, played by Fil Formicola, has almost no lines and gets very little screen time at all! There's a partial reason for that: the script is more interested in his enforcer, the magnetic Vincent Pastore of "Sopranos" fame, and there proves to be a second, more interesting defendant placed on trial before the hour is up...
As a reviewer before me noted, this one explores why McCoy does what he does: does he care about justice, or does he just care about winning? He's confronted with that question several times in this episode, by Leibman's character, by ADA Claire Kincaid (Jill Hennessy), and by Jessica Walter as Leibman's wife (both in the show and in real life, no less).
McCoy is smiling in early scene opposite Leibman, but there's not a smile to be found by the time this one's over with...