Steven Bochco was the executive producer (http://www.imdb.com/title/tt0090466/board/flat/231150705?p=1) for Seasons 1-3 (as well as a portion of Season 6 before stepping down again) and David E. Kelley took over for him in Season 4 and continued to hold that spot through Season 5.

Bochco era

Bochco era. Show jumped the shark after he left and that is when Michael and Grace broke up.