The flashbacks in the recent Boston Legal episodes were from a two-part episode of the series "Studio One".
The episode was called The Defender, and, as in the Boston Legal episode, Ralph Belamy's character was the father of the William Shatner episode.
That show was written by Reginald Rose.
You can find a little more about this show here in IMDb.
What was really great was how they worked these scenes into the episode. David E. Kelley is a genius at writing dialog and even in supervising other writers in getting to that dialog.
Some of Shatner's performance was a bit stilted (no surprise there when he's doing drama) but they really made the character work in this situation.
