Martin Ginsburg, a Georgetown University tax law professor whose blind date more than a half-century ago with a quiet undergraduate named Ruther Bader blossomed into an enduring marriage, died yesterday of complications from metastatic cancer at his home in Washington. He was 78.

Mr. Ginsburg joined the Georgetown faculty in 1980 and was considered one of the nation's preeminent tax law experts for his mastery of the Internal Revenue Code's intricacies. He also served as the sounding board, moral supporter, and intellectual sparring partner for his wife, Ruth Bader Ginsburg, as she rose to become history's second female Supreme Court justice.

They celebrated their 56th anniversary Wednesday. The foundation of their relationship, they both said, was mutual respect and equality, and a willingness to share domestic duties.

Soon after their wedding, young Army Lieutenant Martin Ginsburg was assigned to an artillery unit at Fort Sill, Okla. One night, his wife presented him with a dish he immediately deemed inedible, he later told the Washington Post.

"What is it?" he asked.

"It's tuna fish casserole," she replied.

From then on, Mr. Ginsburg took over responsibility for dinner, finding inspiration in an English translation of an Escoffi-er cookbook that had been a wedding gift. "As a general rule," Mr. Ginsburg told The New York Times in 1997, "my wife does not give me any advice about cooking, and I do not give her advice about the law."

Martin David Ginsburg was born June 10, 1932, in Brooklyn, N.Y., and grew up in Rockville Center on Long Island. His father was vice president of the Federated department store chain.

He went to Cornell University in New York, where he studied chemistry. His roommate set him up on a blind date with Ruth Bader. Later, she recalled that Mr. Ginsburg, a gregarious varsity golf player, was "the only young man I dated who cared that I had a brain."

He received a bachelor's de spouse of high court justice gree from Cornell in 1953, and the Ginsburgs were married shortly after her graduation a year later. That day, Mr. Gins-burg's mother approached the bride and took her hand. "I am going to give you some advice that will serve you well," the mother-in-law said. "In every good marriage, it pays sometimes to be a little deaf." As she spoke, she placed a set of wax ear plugs in the young bride's palm.

"I have recalled that advice regularly," Ruth Bader Ginsburg wrote in a 2002 anthology of essays, "The Right Words at the Right Time." "Tempers momentarily aroused generally subside like a summer storm."

Not long after their wedding, the couple headed to Fort Sill. In a 1993 interview with the Post, Mr. Ginsburg recalled that his military career got off to a slow start.

"How much experience have you had in artillery?" a captain asked upon his arrival. "I will level with you," Mr. Ginsburg said. "The first artillery piece I have ever seen in my life is the one I see through your window, on the back of that jeep."

"Son, that's an automatic fence post digger," the captain replied.

After his Army service, Mr. Ginsburg and his wife attended law school at Harvard University.

He graduated in 1958 and joined the New York firm Weil, Gotshal & Manges. Ruth Bader Ginsburg left Harvard and finished law school at Columbia University.

Mr. Ginsburg practiced tax law in New York and was an adjunct law professor at New York University until deciding in 1978 to pursue teaching full time. He joined the faculty at Columbia's law school and moved to Georgetown in 1980 after his wife became an appellate judge in Washington. He continued to practice as a tax lawyer.

In 1984, Mr. Ginsburg helped Ross Perot resolve tax problems involving the acquisition of his company, Electronic Data Systems, by General Motors. Mr. Ginsburg refused to accept payment from Perot for his efforts. Instead, Perot endowed a chair at the Georgetown law school in Mr. Ginsburg's honor.

Besides his wife, Mr. Ginsburg leaves two children, Jane Carol Ginsburg of New York and James Steven Ginsburg of Chicago; a brother; a sister; and four grandchildren.

Mr. Ginsburg said he was proud of his wife's accomplishments and had no regrets about the compromises they made for each other. "I have been supportive of my wife since the beginning of time, and she has been supportive of me," Mr. Ginsburg told the Times in 1993. "It's not sacrifice; it's family."