But that is the "average American" lawyer.  

For there to be a liberal 'average' there must be the conservative end of the spectrum as part of that 'average'!

And your conclusion is based on:  

"Researchers matched the largest database of federal campaign contributions made by individuals since 1979, with the Martindale-Hubbell directory, the largest database of lawyers in the country."

It says nothing about those of us who became lawyers prior to 1979 and it is based only on Martindale-Hubbell.

And millions of lawyers are not in Martindale-Hubble and thousands of those who are do not make federal campaign contributions.  

It is a self-selected database.  It costs $599 to have your rating displayed.  

http://kevin.lexblog.com/2009/10/20/martindale-hubbell-ups-the-ante-price-tag-for-lawyer-to-display-rating-online-goes-from-50-to-599/

It's like relying on a database with only the attorneys who take out yellow page ads!