After Richard J. Clarke, a 41-year-old father of four from Haverhill, Mass., went on a drinking binge in 1994 and committed suicide, his widow sued his health insurance plan for wrongful death. She alleged the health plan had refused to pay for a detoxification program after an earlier suicide attempt.

But a judge threw out the case, saying federal law gave the health plan "a shield of immunity."

"The tragic events set forth in Diane Andrews-Clarke's complaint cry out for relief," U.S. District Judge William G. Young wrote in a 1997 decision. "Nevertheless, this court has no choice but to . . . slam the courthouse doors in her face and leave her without any remedy."

Whether patients or their survivors should be able to file such lawsuits will be at the heart of the debate this week as the Senate takes on the long-simmering question of how to regulate managed care.

After years of clamor about the growing power of health maintenance organizations (HMOs) and other cost-cutting insurers, Senate Republicans and Democrats have drafted competing versions of a "Patients' Bill of Rights." The rival plans address a variety of issues, including coverage of emergency room visits, access to medical specialists, and the right to an independent review when a health plan refuses to pay for medical services.

Many states have already tackled these issues, producing a patchwork quilt of inconsistent regulations. But state consumer protections do not help an estimated 48 million Americans whose health plans are exempt from state regulation.

In the Senate, Democratic and Republican proposals differ on such basic points as whether patients' rights should ordinarily apply to people in HMOs -- Republicans would defer to the states -- and how much power managed-care companies should wield over doctors' decisions. Generally, Democrats are pushing more aggressive and potentially costlier measures.

Nowhere is the partisan split sharper than on the question of lawsuits.

Under a 1974 law called the Employee Retirement Income Security Act (ERISA), an estimated 125 million Americans with employer-sponsored health benefits are for the most part prohibited from suing their health plans in state courts. Suits over coverage decisions must be brought in federal courts, where the health plans are shielded from punitive damages and awards for pain and suffering, lost income and the like. Typically, the only thing plaintiffs can collect, besides legal fees, is the value of the care that was denied.

The ERISA law was written before managed care transformed the way health care is delivered. Then, disputes about coverage decisions typically centered on payment of medical claims after the patient had received the care. Now, managed-care organizations try to influence the way patients are treated, and a decision to deny coverage is more likely to stop the patient from getting the disputed care.

Senate Democrats are fighting to eliminate health plans' "immunity" from damages under ERISA, arguing that they, like other businesses, should be legally accountable for their actions. Senate Republicans say that approach would invite a flood of litigation, driving up premiums and prompting some employers to drop health benefits.

Democrats have sided with an unlikely alliance of physicians and personal injury lawyers, in addition to consumer groups, while Republicans stand with employers and the managed-care industry.

Consumer advocates say the threat of damages would be the strongest deterrent to the kind of penny-pinching that could compromise patient care. If the only thing health plans stand to lose in litigation is the cost of the care they denied, "they have every financial incentive to delay and delay and deny and deny," said Ronald F. Pollack, executive director of Families USA, a consumer group.

The managed-care industry sees it differently. "Our view is that this provision does nothing to help with health care quality . . . but is really much more of a trial lawyers protection provision," said Susan Pisano, spokeswoman for the American Association of Health Plans, an industry group. Much of the managed-care industry has embraced external administrative appeals as a quicker and less onerous alternative.

In most states, people insured through state and local governments and individual policies have the right to sue for punitive damages, and some have won huge awards.

In 1994, a jury assessed $89.3 million in damages against a California HMO that refused to provide an autologous bone marrow transplant for a breast cancer patient who later died. The case subsequently was settled for an undisclosed amount.

This year, the widow of David Goodrich, a county prosecutor in San Bernardino, Calif., won a $120.2 million judgment against Aetna U.S. Healthcare of California Inc. A jury found that the insurer breached its responsibility in his treatment for a rare form of stomach cancer. Aetna is appealing.

But big jury verdicts are just part of the potential price of expanding the right to sue, analysts say. The threat of liability could inhibit health plans' efforts to eliminate unnecessary care, analysts say, because it could make them more afraid to say no to doctors and patients.

To be sure, advocates of the right to sue champion it in the belief it would change the way managed-care companies do business. "If they were accountable for their conduct, they would never behave the way they currently behave," said attorney Michael Bidart, who won the $120.2 million judgment against Aetna.

In the aftermath of the $89.3 million judgment for California teacher Nelene Fox, many health plans made it easier for patients to get autologous bone marrow transplants, according to the Congressional Budget Office. More recently, scientific research has cast doubt on the benefit of such procedures for women with advanced breast cancer.

Permitting more patients to sue over denials of coverage would almost certainly raise health care costs; the question is how much.

Princeton health economist Uwe Reinhardt said that the financial impact is impossible to know, but he suspects it would be profound. "In the end, we're back again to basically the open-ended deal where the individual physician makes a judgment and no one dares question it," he said.

Jeff D. Emerson, former chief executive of NYLCare Health Plans of the Mid-Atlantic, sees a more modest financial effect, though he foresees other unintended consequences. "I'm not going to make the argument that it's going to be a lot of money."

The Congressional Budget Office, which is responsible for predicting the cost of legislation, said on this question "the supporting data are extremely limited or nonexistent." Ultimately, the CBO projects, removing the barrier to liability as Senate Democrats propose would increase premiums by 1.4 percent.

Aetna U.S. Healthcare, one of the largest insurers, shares the view that liability would drive up premiums. But currently, "we would charge the same premium to a customer with the ability to sue as we do those who do not have the ability to sue," spokesman Walter J. Cherniak Jr. said.

Why? "Those judgments to date have been a very small component of overall health care costs," Cherniak said.

The House has resisted past efforts to expand the right to sue, and it is not clear when it will return to the subject of managed care. The entire Senate debate may amount to little more than a rehearsal of sound bites for the next campaign.