Gerald A. Feffer, a Washington lawyer who drew national attention for his spirited defense of Leona Helmsley, the billionaire hotel empress and reputed “Queen of Mean,” on charges including tax evasion, died Feb. 13 at his home in the District. He was 70.

He had complications from Parkinson’s disease, said his son Andy Feffer, the chief operating officer of the Washington Nationals.

Mr. Feffer’s four-decade legal career included stints as an assistant U.S. attorney and, in the Justice Department during the Carter administration, as deputy assistant attorney general for criminal tax investigations. He was best known as a criminal tax defense lawyer with the Washington firm of Williams & Connolly from 1986 until his retirement in 2010.

Mr. Feffer’s clients included basketball star Michael Jordan and the Church of Scientology, which, with his counsel, won a protracted battle with the federal government to be recognized as a religious tax-exempt organization.

Mr. Feffer achieved many of his victories out of court and out of the public eye. The Helmsley trial in 1989 was a notable exception — a media extravaganza fueled at least in part by the excesses of his client, a woman so roundly reviled that she at times drew comparisons to Marie Antoinette.

Gerald A. Feffer, a high-powered Washington lawyer whose clients included hotel empress Leona Helmsley, died Feb. 13. He was 70. (Family photo)

Helmsley had presided since 1980 over the national hotel chain owned by her third husband, Harry B. Helmsley, a real estate mogul whose properties were valued at $5 billion.

She was accused of evading millions of dollars in taxes by charging personal expenses and luxuries to the Helmsley hotel chain. During the trial, newspaper readers and television viewers across the country became intimately acquainted with tales of her alleged villainy.

A maid testified that Helmsley had once declared that “only the little people pay taxes.” (Helmsley denied having made the remark.) She was said to have fired one employee while she was being fitted for a dress. A witness testified that clothing worth $10,000 was billed as hotel “uniforms.”

Faced with the challenge of defending her before a jury, Mr. Feffer called upon a time-honored courtroom technique: embracing a client’s faults as a way of wresting them from the legal adversary.

“If she should stumble on a speck of dirt in a hotel room,” Mr. Feffer said, “all hell breaks loose.” But “ladies and gentlemen,” he told the jury in his memorable opening statement, “I don’t believe Mrs. Helmsley is charged in the indictment with being a tough [expletive].”

(Departing from typical courtroom decorum, Mr. Feffer used a word that, as was sometimes said in the context of Helmsley, “rhymes with rich.”)

Jim Bruton, a Williams & Connolly partner who assisted Mr. Feffer with the Helmsley case, recalled reading a draft of the opening argument. “Are you sure you want to say this?” he asked.

Mr. Feffer was sure.

“He had thought it through for a long time,” Bruton said in an interview. “There wasn’t that possibility of trying to take her and make her lovable.”

Helmsley was convicted on 33 of 41 counts, including tax evasion, mail fraud and conspiracy to defraud the government. A judge sentenced her to four years in prison and fined her more than $7 million. Helmsley, who died in 2007, was acquitted of extorting cash and merchandise from suppliers, the most serious charge brought against her.

“You could just see that she was someone who was hard to please, even someone of [Mr. Feffer’s] abilities,” said Jim DeVita, the former assistant U.S. attorney who prosecuted Helmsley. “I surely had respect for him.”

Gerald Alan Feffer was born April 24, 1942, in Washington. He spent part of his adolescence in Europe, where his father was a U.S diplomat.

He was a 1964 business administration graduate of Lehigh University in Bethlehem, Pa., and a 1967 graduate of the University of Virginia law school.

His first marriage, to Rosemary Dileo, ended in divorce. Survivors include his wife of 29 years, Monique E. Yingling of Washington; a son from his first marriage, Andy Feffer of Chevy Chase; two sons from his second marriage, John Feffer and Keith C. “Casey” Feffer, both of Washington; two sisters; and two grandchildren.

After her conviction, Helmsley repaid Mr. Feffer for his efforts with some harsh words in an interview with Playboy magazine. A chief criticism was that he publicly revealed her long-hidden age.