* First Monday in October has become a little drab in its transition from stage to screen. It's still a thoughtful and amusing show, with its feisty confrontations between a liberal justice of the Supreme Court and his newest associate, who's a staunch conservative and a woman to boot. (Just like real life?) And there are sparkling performances by Walter Matthau and Jill clayburgh , who are every bit as spunky as Henry Fonda and Jane Alexander were in the Broadway version. But the continually salty language seems forced, and there are some visual excesses in a key scene involving a pornographic film under judgement by the court. Ronald Neame directed, rather woodenly. The crafty dialogue, like the original play, is by Jerome Lawrence and Robert E. Lee.