WASHINGTON (AP) — In 16 appearances before the Supreme Court, Donald Verrilli has advocated for the rights of death row inmates and has successfully argued fine points of telecommunications law in cases with billions of dollars in the balance.

Now as the Obama administration's solicitor general, Verrilli faces what for any lawyer would be the challenge of a lifetime: persuading at least five Supreme Court justices to uphold the president's overhaul of the nation's health care system.

Verrilli is known as a zealous advocate with an intense work ethic, yet with an open, engaging manner in court and a calm demeanor. His style may be just the right touch in a politically charged case that represents a wild card tossed into the middle of a presidential campaign.

The 54-year-old one-time Supreme Court clerk, who became solicitor general last June, "comes across as a very straight shooter; there's a conversational feeling when he stands up there; he's completely honest and straight-forward," says Washington attorney Theodore B. Olson, who has argued 58 cases before the justices and served as solicitor general under President George W. Bush.

Verrilli has always been "just as gracious and friendly when he was your opponent in court as when he was your ally," recalls Washington lawyer Peter Keisler, who was both in the 1990s when he and Verrilli represented separate telecom companies that were sometimes at war and sometimes allies slugging it out with competitors.

The son of a lawyer, Verrilli grew up in Connecticut, received his bachelor's degree in history, with honors, from Yale University in 1979 and his law degree in 1983 from Columbia Law School, where he was editor-in-chief of the Columbia Law Review.

He clerked for Supreme Court Justice William Brennan.

In 1994, as special counsel to President Bill Clinton, he assisted in the confirmation process for Stephen Breyer, one of the justices who will hear Verrilli's argument in the health care case in late March. Verrilli's varied clients have included the House Democratic leadership.

In the late 1990s, Verrilli immersed himself in court battles over a federal law aimed at spurring telecommunications competition. Colleagues recall he did a masterful job explaining legal subtleties, public policy and technical engineering issues in easy-to-understand terms.

"Don was terrific at cutting through all the technical jargon and conveying with real conviction that, at its heart, these cases weren't dry disputes about telephone technology, but about ensuring competition," said Washington attorney Joseph Guerra, who has known Verrilli more than 20 years.

The advent of the Internet set off major legal battles over online piracy and led to perhaps Verrilli's biggest Supreme Court victory to date.

Representing motion picture studios and music recording companies, Verrilli introduced a legal doctrine — inducement — that had never been applied in such a context. Verrilli argued that a developer of file-sharing software was actively encouraging consumers to steal.

"This was a new technology, and Don was really taking his argument out of traditional legal paradigms. He used that novel theory to expose the real core of what was offensive about the defendants' conduct," said Michael DeSanctis, managing partner at the Washington office of Jenner & Block, where Verrilli spent two decades.

The 9-0 ruling that Verrilli won in Metro-Goldwyn-Mayer Studios Inc. v. Grokster Ltd. enabled Hollywood and the music industry to sue technology companies that encourage customers to steal music and movies over the Internet.

Traveling the country for corporate clients, Verrilli came across a struggling community of appellate lawyers in the South who at great financial cost took up the cases of indigent death row inmates who had inadequate legal representation at trial.

Verrilli himself toiled more than a decade on the case of death row inmate Kevin Wiggins, ultimately winning a precedent-setting Supreme Court decision that spared Wiggins from execution. Verrilli's painstaking investigation turned up strong evidence Wiggins endured a horrific childhood of violence at the hands of his mother and of repeated rapes of Wiggins by members of two foster families who took him in.

In a 7-2 decision, the Supreme Court set aside Wiggins's death sentence on grounds the convicted murderer's right to effective counsel had been violated by Wiggins's prior lawyers. Attorneys in death penalty cases, the court ruled, must conduct a reasonable and diligent background investigation.

A factor in the outcome was Verrilli's "absolutely humbling degree of personal passion for Kevin Wiggins and for the issue — assuring effective assistance of counsel in death penalty cases," said DeSanctis. "That's something that a lot of appellate lawyers don't bring to a case."

Paul Smith, a long-time friend and colleague, called Verrilli a perfectionist — relentless about "getting things just right."

"That's true to the point where he has a bit of a reputation of still making changes in briefs after they already ought to be at the printer," laughed Smith, chair of Jenner & Block's appellate and Supreme Court practice.

In February 2009, President Barack Obama appointed Verrilli as an associate deputy attorney general. He moved to the White House in 2010 and as an associate White House counsel dealt with immigration, health care, financial regulation and the Gulf oil spill. Last year, Verrilli was confirmed to replace then-Solicitor General and current Supreme Court Justice Elena Kagan.

The outcome of the court battle over health care is impossible to predict, and so is the political impact.

If Verrilli wins, it might help Obama get re-elected — or become a rallying cry for his political opponents.

Regardless, with Verrilli doing the bulk of the arguing for the administration, "everyone will know that the government is being represented in the best possible way," said Keisler.