UPDATE: For a 2021 update, see this post.

The answer: in 2012, attorneys at most law firms preferred President Obama, by a substantial margin. Charts and analysis below.

I culled Federal Election Commission data from the 2012 presidential election.  The data set includes firms that recorded ten or more attorneys who contributed to a candidate. As FEC data is self-reported, there is essentially no standardization in reporting. Self-titled "attorneys" and "lawyers" are included. Attempts were made to glean common misspellings or alternative ways of reporting an individual's or firm's name when aggregating totals.

(For reference, I used the same methodology and computer program that was used to examine political contributions of attorneys in government agencies.)

The first chart, above, is the bulk of this research. This chart is limited to firms with at least 15 contributing attorneys. The percentage contributions are of contributions between Mr. Obama and Governor Romney. (That is, contributions to third-party candidates were excluded.) 

I did the same with the top 100 of the NLJ350 firms. All firms but one had at least ten attorneys who contributed, and they are included below.

The median participation rate was around 11.2% at these firms. But this probably underestimates the participation rates simply because of the self-reporting issue identified above--attorneys at some firms aren't included in their firm because of a misspelling. And for some individuals whose names are misspelled, it may overstate the number of unique contributors.

But the firm that had by far the highest participation rate based on this methodology was Morgan & Morgan, an Orlando personal injury firm. (Its turnout rate may appear higher than other firms simply because of the easy of spelling the firm's name.) It has 234 attorneys according to NLJ, and I identified 104 attorneys who contributed (102 to Mr. Obama, 1 to Mr. Romney, and 1 elsewhere) for a 44.4% contribution rate, 99% of them to Mr. Obama. Morgan & Morgan founder John Morgan was one of Mr. Obama's biggest bundlers, bundling at least $500,000 for the reelection campaign. Morgan & Morgan is also the new home of former Florida governor Charlie Crist, who bundled between $100,000 and $200,000 for the President's reelection efforts.

I also made a chart for the Vault 100.

What to do with this data?  Well, should corporations contracting for legal services care about whether the attorneys' ideological perspectives coincide with the interests of their clients? Does a firm's political perspective equal the sum of its contributing-attorney parts? Perhaps it's just an open question of what to do with all this data.

UPDATE: And we could have more disclosure data soon: see this post about a new proposal for corporate and labor union disclosure.