Brian Hall never wanted to rely on the government for his medical coverage, because he had seen how Medicare restrictions limited his mother’s health care.

But shortly before he turned 65 in January, the retired federal computer specialist realized he had little choice but to enroll in Medicare Part A, the federal government’s hospitalization insurance for the aged and disabled.

That’s because Social Security rules require its beneficiaries to accept Part A at age 65—or give up their Social Security benefits. The rules also require the repayment of all Social Security retirement benefits already collected, if Part A coverage is refused.

“I was astonished to find these rules exist,” Hall said. “It seems un-American to force people to take a benefit they don’t want.”

Hall, who lives on a small farm in Catlett, Va., accepted the coverage he never wanted. And he did something else he never thought he would do: He filed a lawsuit that’s gaining traction in federal court.

If his suit challenging the Social Security rules is successful, it could create new options for older people who want a private policy, not Medicare’s free Part A coverage, as their primary hospitalization insurance. It also could raise costs for younger people in the group medical policies that these seniors join as the plans pay out more to cover the older beneficiaries’ health care costs.

Hall said he accepted Medicare because he couldn’t afford to repay the Social Security benefits he has collected since age 62, and he also needs his future benefits. But by accepting Medicare he could no longer contribute to a tax-free health savings account—because a law prohibits having both—which he said would cost him about $20,000 over 10 years in lost tax benefits and interest. Also, he said, his group plan under the Federal Employees Health Benefits Program scaled back his coverage because Medicare is now his primary provider.

Other federal retirees, including former House Majority Leader Dick Armey, found themselves facing the same choice and joined Hall’s lawsuit.

“I was stunned to [learn] I had no choice but to sign up for Medicare,” said Armey, a Texas Republican. “I had spent my entire life thinking I wouldn’t do so. … Then I learned—to my absolute amazement—that if I didn’t sign up for Medicare, I would lose my Social Security.”

The Social Security Administration lets beneficiaries opt out of Part B, supplemental Medicare coverage that requires payment of a premium. But it has no mechanism for opting out of Part A, which requires no premium.

The Social Security Administration and the U.S. Department of Health and Human Services, the defendants in Hall’s lawsuit, said in court documents that they’re not required to provide “any mechanism for individuals who are entitled to monthly Social Security benefits to avoid or extinguish the resulting automatic entitlement to Medicare Part A.”

Both agencies and their attorneys declined to comment. In court, they pointed out that retirees are free to opt out of Medicare Part A if they don’t file for Social Security benefits or leave the system and repay any retirement benefits they’ve already collected.

Norm Rogers, the retired founder of a California semiconductor company who now lives in Chicago, chose to do just that. At age 68, he hasn’t filed for Social Security benefits because he doesn’t want Medicare. He said he relies on private insurance, but resents losing benefits for which he paid taxes.

“I paid $400,000 over my working life for Social Security and Medicare, and I’m not going to get anything for it,” he said.

Rogers was among the retirees who joined Hall’s lawsuit, which is partially supported by a nonprofit group called the Fund for Personal Liberty. In September, the judge dismissed Rogers’ and another plaintiff’s claims, saying they hadn’t “suffered injury-in-fact” because they hadn’t filed for Social Security or accepted Medicare.

At the same time, though, U.S. District Judge Rosemary Collyer handed the three remaining plaintiffs a significant victory by rejecting the government’s request to dismiss the case altogether. The government responded by asking the judge to reconsider at least part of her ruling and to avoid making a decision in the case without hearing testimony. The plaintiffs’ attorney, Kent Masterson Brown of Lexington, Ky., said he expects the case will be argued early next year in the U.S. District Court for the District of Columbia.

“As a federal agency, you can’t write these rules that affect so dramatically the lives of those who collect Social Security and Medicare and deny them Social Security when the statutes make both of these programs voluntary,” Brown said. “My clients want their Social Security because it’s their property.”

Armey and others also have questioned why the government wants to keep retirees in Medicare. The program’s trustees reported in May that its trust fund will be exhausted by 2017 unless Congress acts to raise revenues or reduce payments. At that point, tax payments would cover only 81 percent of scheduled benefits.

“You would think … they would be hugging me for not wanting to sign up for Medicare,” said Armey.

No one knows for certain how many of the 37.8 million Americans over age 65 on Medicare would drop their government coverage if they could. But Hall’s lawyer claims Medicare would save $1.5 billion a year if just 1 percent of eligible seniors declined hospitalization insurance.

Shifting seniors from Medicare to other forms of insurance could drive up costs for policyholders younger than 65. That’s because now, private insurance typically provides only supplemental coverage once a policyholder becomes eligible for Medicare. If seniors with their higher medical costs could join a private group plan, premiums of younger members would likely rise. The insurance industry’s trade association, America’s Health Insurance Plans, declined to estimate the potential impact.

Armey said health plans will have to face this issue soon, because he expects the plaintiffs to prevail in court. If they do, the former congressional leader said he expects he will have another fight on his hands to get full coverage from his health plan when he could have Medicare at no additional cost to himself.

“I will probably be the first test case, and I will insist on getting my full coverage,” he said.

Laura Mecoy has written about health care issues for more than 25 years.