Lawyer and Horseman Joseph Muldoon Jr.

Joseph A. Muldoon Jr., who died March 16 of prostate cancer at his home in Poolesville, knew practically everything about the arcane field of savings and loan regulation, but he knew even more about horses.

Mr. Muldoon, 76, was a lawyer who helped his clients sort out the regulatory mess resulting from the 1980s savings and loan debacle. Two years ago, he came out of retirement to help alert Congress and the media to the potential takeover of operations at 22 U.S. ports by a company from the United Arab Emirates. The resulting uproar forced congressional reassessment of security rules and policies governing international corporate takeovers.

For all his achievements in law and finance, however, Mr. Muldoon was perhaps better known as one of the Washington area's leading horsemen.

"Horses were the love of his life," said his law partner, George W. Murphy Jr. "They were the only thing that diverted him from his practice."

Mr. Muldoon began riding as a boy and worked his way through college and law school by training horses for show jumping and fox-hunting. For the past 50 years at his farms in Montgomery County, he raised, trained, traded and rode horses.

After taking up polo in 1970, he bought the Potomac Polo Club in the 1970s, moved its headquarters to his Poolesville farm and became a leading advocate for the aristocratic and dangerous sport.

In 1980, Mr. Muldoon told The Washington Post that he played in a match 10 days after breaking his cheek, "with wire and Teflon in my eye socket."

The 6-foot-5 Mr. Muldoon often played polo with his three sons, but his son Michael was struck in the head with a mallet in 1977 and died two years later. Mr. Muldoon continued undaunted but organized annual charity games to benefit brain and spinal cord research.

Throughout the 1980s, he brought the world's best players and ponies to Poolesville for matches that were considered the most competitive in the United States. Thousands of spectators flocked to Mr. Muldoon's farm for the games, which featured top players from Argentina, Mexico, Pakistan and the United States. Celebrities gathered at the VIP tent, and after one match the smooth-talking Mr. Muldoon sold a pony to Sylvester Stallone.

"He had one of those pleasing personalities, and it showed with his horses," said a longtime friend, Tyler Abell, who was chief of protocol under President Lyndon B. Johnson. "Dealing with horses is in some respects like dealing with people. He always said the horse business was better preparation for the law than all his education."

Joseph Arthur Muldoon Jr. was born Aug. 24, 1931, in Waltham, Mass., and grew up in Washington. He was a graduate of Gonzaga College High School and Georgetown University's School of Foreign Service. He worked as a horse trainer and U.S. Capitol Police officer while attending Georgetown Law School, from which he graduated in 1955.

Mr. Muldoon was a hearing officer for the Federal Home Loan Bank Board for several years before entering private practice. He founded Sloane & Muldoon (now Muldoon Murphy & Aguggia) in 1968 as one of Washington's first firms to specialize in licensing and regulatory matters affecting the thrift and savings and loan industry. When more than 1,000 savings and loan institutions failed during a financial collapse in the 1980s, Mr. Muldoon helped the surviving thrifts merge and get back on their feet.

In 2006, a year after officially retiring from his practice, Mr. Muldoon had one of his greatest legal triumphs. He and his son Joseph A. Muldoon III were representing a Florida-based port terminal operator when they learned that Dubai Ports World, a company owned by the government of the United Arab Emirates, had received a secret national security review and was about to take over the operation of 22 U.S. ports.

Mr. Muldoon and his son knocked on doors on Capitol Hill, taking on big-name lobbyists and the White House. They persuaded senators and congressmen of both parties that national security could be compromised by allowing an Arab-owned company to run U.S. ports during the war on terrorism. In the end, the political fallout over the deal prompted Congress to tighten laws governing international corporate takeovers, and Dubai Ports World sold its interest in the ports to a U.S. firm.

Afterward, Mr. Muldoon retired for good to his farm. Last year, one of the horses that he and his wife trained, Memento Mori, won jumping championships in five states.

His marriage to Caroline C. Muldoon ended in divorce.

Survivors, in addition to his son Joseph, of Poolesville, include his wife of 14 years, Alyse B. Muldoon of Poolesville; two children, Mary Louise Muldoon and Charles Muldoon of Poolesville; two stepchildren, Lanah Hamilton of Poolesville and Tristan Hamilton of Loma Linda, Calif.; two sisters, Mary Elizabeth Muldoon of Rockville and Patsy M. Murphy of Atlanta; and a grandson.