Lawyers contribute money 3:1 to Democrats than to Republicans.

That leaves us with two possibilities: (1) Corporate lawyers are D, your theory is largely correct, but references to "trial lawyers" being D are very misleading. (2) Corporate lawyers are not D (I now guess evenly split), but aren't politically active. Some politics (you claim D) benefits them by accident. I lean towards #2.

A crude measure is politicians. According to this source there are 50% more Democratic congressmen who are lawyers than Republican congressmen who are (and 15% more D than R that term). Of course you get the wrong answer if you try to figure out the politics of entertainers by looking at politicians. But even if they aren't representative of lawyers, I suspect that all those R lawyer congressmen are doing things in the interests of lawyers.