Of the 10 highest-grossing Washington, D.C., lobbying outfits in 2012, six were law firms. And the highest-grossing of all is the law firm Patton Boggs, which has generated nearly a half-billion dollars in lobbying revenue since 1998. The firm set the template for the seamless blend of lobbying and legal services that's now commonplace in the nation's capital: Of the Am Law 200 firms with Washington, D.C., offices, the majority have lobbying capabilities (or at least say they do).

In 1966, when Thomas Boggs Jr. joined James Patton Jr.'s firm four years after its founding, most D.C. law firms didn't lobby, except on tax issues. Lobbyists, who then numbered in the dozens, were almost exclusively former government officials working out of small shops.

For Boggs, the idea of pursuing lobbying work was about playing to his strengths. He was only one year out of Georgetown University Law Center when he joined Patton's firm, so he didn't have years of legal practice under his belt. But as the scion of a Louisiana political family and former staffer in the Johnson administration, he knew his way around Washington, D.C. Asked why he went after lobbying work, Boggs quips, "We had a need for business," before pivoting to his more polished response: "We thought being lobbyists made us better lawyers and being lawyers made us better lobbyists."

In the 1970s that strategy began paying off with high-profile lobbying assignments for the Alaska Pipeline and the $1.5 billion federal bailout of Chrysler Group, among other matters. Boggs recalls: "For a good while we had the field all to ourselves." No more.