Millard Midonick, the former Manhattan Surrogate best known for presiding over the dispute of painter Mark Rothko’s estate, died Jan. 18 in his sleep. He was 99.

His law career spanned more than 70 years. In addition to the Rothko case, Midonick handled disputes over the estates of composer Igor Stravinsky and poet W.H. Auden.

Rothko, an abstract expressionist artist, committed suicide in 1970 and the battle among executors and his children for control of his estate lasted for four years. At the time, the estate was worth more than $30 million.

Midonick left the bench in 1982 at age 68, a year and a half shy of reaching the mandatory retirement age of 70, to join Willkie, Farr & Gallagher as of counsel.

At the time, he complained to The New York Times about surrogates’ low salaries compared to some of the junior partners who appeared before him. But of greater concern to him was the retirement age: “I do not want to go out to pasture,” he said. “I was an intercollegiate athlete once, and I’ve decided not to grow old. I find that when people retire, I get their wills in three years.”

Midonick himself never retired. After several years at Willkie, he served as of counsel to Fensterstock & Partners on trusts and estates cases. He was a regular presence in the office until last year, said firm founder Blair Fensterstock, who had been one of Midonick’s mentees.

Midonick was born and raised in New York City. He attended Columbia University, then Columbia Law School, where he was editor of the law review and graduated in 1934.

For the first decade out of law school, Midonick worked as a trial examiner and attorney for the National Labor Relations Board. He also served for the U.S. Coast Guard in World War II as commanding officer for the U.S.S. Brownsville, a patrol frigate destroyer in the Pacific Ocean.

In 1946, he joined Polier Midonick & Zinsser as name partner, working on trusts and estates as well as labor arbitration. He took a yearlong break from the firm to serve as a judge on the Municipal Court of the City of New York.

In those years, Midonick became active in reforming the city’s Democratic party and in 1953 helped co-found the Samuel J. Tilden Democratic Club for Manhattan’s East Side. In 1962 he was appointed to the Family Court by Mayor Robert F. Wagner. He served there until he was elected to the Surrogate’s Court in 1971.

Midonick met his wife Jill Claster, a professor of medieval history at New York University, in 1977 through a mutual friend whose wedding he officiated. They married in 1979.

“He loved being a judge,” Claster said in an interview. “He was a very happy man as long as he was practicing law.”

Midonick remained involved with Columbia Law School throughout his career, serving on its Board of Visitors and mentoring law students. He also served as a trustee for Beth Israel Hospital and was involved in the Citizens’ Committee for Children of New York.

He is survived by his wife and several nieces and nephews. Funeral services were held yesterday.