But now we come full circle:

The underlying data: not proprietary (do you really think membership in the DC Bar, of all things, is "proprietary"?).

The presentation of said data on the DC Bar website: presentation is proprietary, data is still not.

But additionally: DC Bar says "if you get this information via this venue, then you're accepting our terms of use which say you can't use the information obtained via this venue to, eg, compile an AVVO-like site."

So on the face of it: only if Avvo is crazy-stupid will Avvo get burned here: the only scenarios in which Avvo gets burned are somewhere between

(a) the DC Bar can show suspicious access patterns that either come from Avvo or come at suspicious times vis-a-vis Avvo's updates

(b) Avvo doesn't have any internal documentation demonstrating from whence they obtained the information that's ticking off the DC Bar (ie: we paid some dudes to re-type the relevant phonebook sections, or paid some dudes to re-type the printed member's directory, etc.)

So the whole thing is pretty silly (at least until more facts emerge).

Edit: Because without some mix of (a) and (b), the DC Bar is ultimately going to have to claim something like "there's no possible way they could have gotten that information besides misusing our site", which I doubt would play well.