David B. Isbell, 82, a partner in the Washington law firm Covington & Burling, former president of the D.C. Bar Association and an adjunct faculty member at the University of Virginia Law School for almost 50 years, died Dec. 7 at Montgomery Hospice in Rockville. He had complications from West Nile virus, said a son, Pascal Isbell.

At Covington & Burling and across Washington’s legal community, Mr. Isbell was known as an authority on legal ethics. From 1982 until 1998, he was chairman of his firm’s professional responsibility committee, and he also advised other law firms on ethical matters.

He addressed ethical questions arising from legal disputes among clients and lawyers and helped devise a disclosure process concerning gifts to the office of the D.C. mayor.

Mr. Isbell joined Covington & Burling in 1957 and retired as a partner in 1998, but he continued as senior counsel at the firm until shortly before his death. Over the years, he participated in a variety of the firm’s pro bono activities, from obtaining veterans’ benefits from a reluctant bureaucracy to making listening devices available for the hard-of-hearing at movie theaters.

David Bradford Isbell was born Feb. 18, 1929, in New Haven, Conn. His father was an architect, but unable to find work during the Great Depression, he moved to France for two years to teach school.

The young David Isbell sowed the seeds of what would become a lifelong Francophilia. He would marry a Frenchwoman, and at the weddings of their three children, he delivered toasts in both French and English.

He graduated from Yale in 1949, served in the Army, then in 1956 graduated from Yale Law School.

In 1983 and 1984, Mr. Isbell was president of the D.C. Bar Association. He was assistant director of the U.S. Commission on Civil Rights from 1969 to 1971, a director of the American Civil Liberties Union and a member of the Disability Rights Council of the Washington Metropolitan Area from 1992 to 2005.

Beginning in 1962, Mr. Isbell taught a seminar on civil liberties at the University of Virginia Law School. He described it to Virginia Law magazine as an examination of the tensions that sometimes arise between individual rights and other interests, both public and private. At his retirement in 2010, he was the law school’s longest-serving lecturer.

Grades in the seminar were based entirely on class participation, and students were expected to learn how to construct logical and persuasive arguments.

Likewise, at the family home in Chevy Chase, Mr. Isbell’s children said they were expected to argue cogently on matters ranging from the trivial to the serious. He was also a stickler on table manners.

Mr. Isbell’s awards included the Thurgood Marshall Award from the D.C. Bar in 2006 and the Wiley A. Branton Award from the Washington Lawyers Committee for Civil Rights and Urban Affairs, which he shared with his wife, Florence B. Isbell in 2001.

His first marriage, to Michele Mazeran, ended in divorce.

Survivors include his wife of 40 years, Florence Bachrach Isbell of Chevy Chase; three children from his first marriage, Pascal Isbell of London, Virginia Isbell of Paris and Nicholas Isbell of Washington; two stepchildren, Peggy Robin and Richard Robin, both of Washington; and 11 grandchildren.

Mr. Isbell’s avocations included singing, ice-skating and tennis. He had a tennis court at home and played competitively even as his years advanced. He was also an avid gardener, and it was his custom every year to give a Fourth of July garden party.

No one knows for sure how Mr. Isbell contracted the West Nile virus, but his children speculated that he could have been bitten by a virus-infected mosquito while gardening.

He was also a graceful dancer who loved to tango with his daughter. Even in the last days of his life, she said, he wanted to tango in the hospice corridors.