In the face of protests on behalf of a chasidic Jew in Rockland County, the Coast Guard has changed its uniform policy to allow service members to wear yarmulkes while on duty.

A tire technician and pilot from Spring Valley, Jack Rosenberg, 35, tried to sign up with a Coast Guard Auxiliary unit in New Jersey last year but was stymied after he told superiors that his religion requires him to wear a skullcap.

After receiving complaints from Senator Kerry, a Democrat of Massachusetts, and Assemblyman Dov Hikind, a Democrat of Brooklyn, the Coast Guard relented. The commandant of the Coast Guard, Admiral Thad Allen, sent a letter to Mr. Kerry last month outlining a more permissive policy. The admiral said the changes were the result of “a thorough review” his agency conducted.

“The Coast Guard listened to reason here,” Mr. Kerry said in a statement to The New York Sun last night. “A yarmulke doesn’t impact anyone’s ability to serve our country. … No one should ever have to choose between honoring their religion and keeping their job, especially our servicemen and women.”

Mr. Rosenberg did not return a phone call seeking comment for this article, but Mr. Hikind said the would-be Coast Guard search-and-rescue pilot was delighted by the agency’s change of heart.

“He is extremely, extremely happy,” Mr. Hikind said. “This is a guy who’s very determined, very nationalistic, very strong in his feelings about America. He felt, ‘Hey, I want to serve my country but I’m also a religious Jew.'”

Mr. Hikind noted that the Coast Guard’s policy was an anachronism of sorts because the other branches of the military have allowed yarmulkes for nearly two decades.

“It just never made sense,” the assemblyman said of the discrepancy.

A Coast Guard spokesman, Chief Petty Officer Daniel Tremper, called the policy change “a good thing” and praised Mr. Rosenberg for raising the issue. “He certainly sounds like someone who wanted to do good for us.”

However, Chief Petty Officer Tremper said the uniform policy was already under review as part of a process to align the Coast Guard with Pentagon practices.”It didn’t necessarily happen as a result of this guy’s complaint,” the spokesman said.

In 1986, the Supreme Court ruled, 5–4, that the armed forces have wide latitude to dictate the uniforms of service members.The justices acted on a legal challenge brought by an Orthodox Jewish rabbi and Air Force psychologist who sought to wear a yarmulke on duty, S. Simcha Goldman.

The Supreme Court’s rebuff to Rabbi Goldman led Congress to act the following year, passing a measure that instructed the military to allow religious headgear. However, the Coast Guard, which comes under Defense Department authority in times of war, never changed its rules.

During outdoor duties, a yarmulke would be usually obscured by a Coast Guard cap. However, the skullcap is exposed indoors, where the official cap is not worn.

In April, the Coast Guard revised a separate policy under which a longtime member of the Merchant Marines, Khalid Hakim, was denied a license because he refused to remove a cap, or kufi, worn by some Muslim men. The agency ultimately granted Mr. Hakim a new license and said it would allow religious headgear in identification photos as long as the gear did not make it difficult to identify the licensed person.

The new rules for Coast Guard service members are tighter. They prohibit headgear bearing any writing and permit only items capable of fitting under a uniform cap. The gear also must be black or the same color as the wearer’s hair. Those restrictions make it unlikely that the new policy for Coast Guard personnel would accommodate headscarves worn by Muslim women and turbans donned by Sikhs.

“I’m not going to say point-blank everything now is kosher and you can do anything that has a religious connection to it,” Mr. Hikind said.