Skadden, Arps, Slate, Meagher & Flom's mergers and acquisitions lawyers in Washington boast an edge over their colleagues in other cities: access to the deep well of regulatory expertise in the firm's D.C. office.

"In energy, communications, health care — any industry where there is greater regulatory scrutiny — I think we have a competitive advantage being inside the Beltway and having face-to-face access to some of the best regulatory lawyers," said partner Pankaj Sinha, who leads the mergers and acquisitions practice in Washington.