Michael Nussbaum, 76, a Washington lawyer for more than 40 years who represented clients in cases ranging from First Amendment issues to a multinational banking scandal, died Oct. 5 at his home in Georgetown.

He had lung cancer, his stepdaughter Wesley Weissberg said.

Mr. Nussbaum retired as a partner of the Ropes & Gray law firm in 2003 after a four-decade career. He continued to practice as counsel to the firm Bonner Kiernan. Among his clients were historian Doris Kearns Goodwin, consumer activist Ralph Nader and journalists including Seymour Hersh, now of the New Yorker magazine. Mr. Nussbaum defended Hersh’s coverage of the 1968 My Lai massacre in Vietnam and the abuse of detainees at the Abu Ghraib prison in Iraq.

In 2008, Mr. Nussbaum obtained a commutation — one of the few granted by President George W. Bush — for hip-hop artist John Forte. Forte had served about half of a 14-year sentence on cocaine charges.

At the law firm Nussbaum & Wald, where Mr. Nussbaum was a partner from its establishment in 1979 until it dissolved in 1996, his clients included the insurer Lloyd’s of London and the liquidators of the Bank of Credit and Commerce International during the massive banking scandal at that institution.

He successfully represented Merrell-Dow Pharmaceuticals in a case involving Bendectin, a drug used to treat morning sickness during pregnancy that some studies linked to birth defects. The U.S. Court of Appeals for the District of Columbia Circuit overturned a $20 million verdict against the company in 1990.

Mr. Nussbaum’s pro bono activity included his work in 1987 on behalf of residents evicted from Edes House, a Georgetown home for the indigent elderly.

Michael Nussbaum was born March 26, 1935, in Berlin. His parent, both Jewish intellectuals, soon fled Germany because of the rise of the Nazi Party and the threat of persecution. Mr. Nussbaum arrived as a 3-year-old in the Kew Gardens neighborhood of Queens, where he grew up.

Mr. Nussbaum was born with a shortened right arm with one finger and no forearm. He overcame the disability, becoming an excellent athlete.

He graduated from Hofstra University in Hempstead, N.Y., in 1957. Four years later, he earned a law degree and, in 1963, a master’s degree in comparative law, both from the University of Chicago.

As a young lawyer, he participated in the movement against the Vietnam War and defended conscientious objectors and others opposed to the draft. In 1967, he defended four students at Howard University who had been accused of organizing black-power activities on campus. He was author of a 1970 book on the legal rights of students.

His first marriage, to Jeannette Smyth, ended in divorce.

Survivors include his wife of 23 years, Gloria Weissberg of Washington; two stepdaughters, Nina Weissberg of Leesburg and Wesley Weissberg of Brooklyn; a brother; and four grandchildren.