The show used a TON Of Broadway actors, which made sense considering, like Law & Order, it was filmed in the New York area (Jersey). B.D. Wong (Tony winner for M. Butterfly and star of the Pacific Overtures revival), Terry Kinney (co-founder of Chicago's Steppenwolf and a Tony nominee as director and actor), and Rita Moreno were regulars for the entire run of the series.
Betty Buckley was on for two seasons I believe as the mother of two of the inmates and she became the prison music director and staged a show. Patti Lupone was the prison librarian for two seasons. Zelko Ivanek played the Giuliani-esque mayor of the city. Edie Falco was a regular as a prison guard for a couple of seasons before her Sopranos schedule got too heavy
And there were stage vets like Uta Hagen, Charles Dutton, Elaine Stritch, Joel Grey, Milo O'Shea, Dana Ivey, Brian F. O'Byrne, John McMartin, Larry Pine, Nastcia Diaz, Ann Meara, Dylan Baker, Mary Alice, Kathleen Widdoes, Kathryn Meisle, Sean Dugan, R.E. Rodgers and many others who made guest appearances at various times over the years. Great show.
"What a story........ everything but the bloodhounds snappin' at her rear end." -- Birdie
[http://margochanning.broadwayworld.com/]
"The Devil Be Hittin' Me" -- Whitney