Filmways, until it was absorbed by Orion Pictures after the first season of Cagney & Lacey, didn't have much of a track record with dramas pre-1982.
In 1965, they gave it a shot with The Trials of O'Brien, with Peter Falk, 3 years before Columbo, as a lawyer. Perry Mason, it wasn't. Not even close. And I don't think America was ready for a lawyer who had more of an interest in horse racing than in defending his clients.
Unfortunately, no complete episodes are available on YouTube. What we can offer, however, is an excerpt from the episode, "A Gaggle of Girls", in which O'Brien gets thrown into a feud between a Catholic parish and a neighboring cafe. Tammy Grimes and David Doyle are among the guest stars.
Trials had potential. It was just probably on the wrong night, or folks just weren't ready for a flawed attorney.