By KATIE THOMAS

Debbie Schork, a deli worker at a supermarket in Indiana, had to have her hand amputated after an emergency room nurse injected her with an anti-nausea drug, causing gangrene. She sued the manufacturer named in the hospital’s records for failing to warn about the risks of injecting it. Her case was quietly thrown out of court last fall.

That result stands in sharp contrast to the highly publicized case of Diana Levine, a professional musician from Vermont. Her hand and forearm were amputated because of gangrene after a physician assistant at a health clinic injected her with the same drug. She sued the drug maker, Wyeth, and won $6.8 million.

The financial outcomes were radically different for one reason: Ms. Schork had received the generic version of the drug, known as promethazine, while Ms. Levine had been given the brand name, Phenergan.

“Explain the difference between the generic and the real one — it’s just a different company making the same thing,” Ms. Schork said.

Across the country, dozens of lawsuits against generic pharmaceutical companies are being dismissed because of a Supreme Court decision last year that said the companies did not have control over what their labels said and therefore could not be sued for failing to alert patients about the risks of taking their drugs.

Now, what once seemed like a trivial detail — whether to take a generic or brand-name drug — has become the deciding factor in whether a patient can seek legal recourse from a drug company. The cases range from that of Ms. Schork, who wasn’t told which type of drug she had been given when she visited the hospital, to people like Camille Baruch, who developed a gastrointestinal disease after taking a generic form of the drug Accutane, as required by her health care plan.

“Your pharmacists aren’t telling you, hey, when we fill this with your generic, you are giving up all of your legal remedies,” said Michael Johnson, a lawyer who represented Gladys Mensing, one of the patients who sued generic drug companies in last year’s Supreme Court case, Pliva v. Mensing. “You have a disparate impact between one class of people and another.”

The Supreme Court ruling affects potentially millions of people: nearly 80 percent of prescriptions in the United States are filled by a generic, and most states permit pharmacists to dispense a generic in place of a brand name. More than 40 judges have dismissed cases against generic manufacturers since the Supreme Court ruled last June, including some who dismissed dozens of cases consolidated under one judge.

Public Citizen, a consumer advocacy group, has petitioned the Food and Drug Administration to give generic companies greater control over their labels, a rule change that could allow users of generic drugs to sue, but the agency said earlier this month that it needed more time to decide. “Congress can make this problem go away, and the F.D.A. could, too,” said Allison Zieve, the director of Public Citizen Litigation Group. “But we haven’t seen signs that either of them is paying much attention.” A spokeswoman for the F.D.A. declined to comment.

The Supreme Court’s ruling, which was split 5 to 4 on ideological lines, has its roots in the Hatch-Waxman Act, the 1984 law that opened the floodgates to generic drugs. That law allowed companies to skip the lengthy process required to approve new drugs if they could prove that the generic drug was equivalent to its brand-name counterpart.

With few exceptions, it also required generic manufacturers to use the same labels — the lengthy list of a drug’s uses, dosages and risks — used by the brand names.

If a problem develops, the brand-name companies are responsible for changing the label, and the generic companies must follow their lead. As a result, the court’s majority ruled, generic companies cannot be held responsible for failing to alert patients to problems with their drug. The dissent, which was written by Justice Sonia Sotomayor, argued that generic companies nevertheless have a responsibility to report problems to the F.D.A. and should be held liable for failing to warn patients.

The ruling came just two years after the Supreme Court established — in Ms. Levine’s case — that, by contrast, brand-name companies can be sued for failing to adequately warn patients.

Ms. Levine was given an injection of Phenergan in 2000 during a visit to a clinic to treat a migraine headache. Her hand and forearm turned black and eventually had to be amputated. Reports had shown that the drug can cause gangrene if it enters an artery, especially if it is placed directly into the vein rather than injected into the muscle or through a diluted intravenous drip. Although the label warned that gangrene could occur if the drug came into contact with arterial blood, Levine argued that the warning did not go far enough.

She sued Wyeth and a Vermont jury awarded her $6.8 million. Wyeth appealed and the Supreme Court sided with Ms. Levine, agreeing that the company could be held liable for failing to adequately warn about the risks of a drug.

Ms. Schork, 52, was given the generic version of Phenergan when she visited the hospital in 2007 with a stomachache and nausea related to her diagnosis of Crohn’s disease.

When a nurse injected the drug into her arm, it entered her artery, and Ms. Schork’s right hand developed gangrene. In asking that the case be dismissed, lawyers for Baxter Healthcare Corporation, which then was one of several companies that made the drug but has since sold its injectable generics to another company, argued that Ms. Schork could not conclusively prove that Baxter had made the drug she took.

The judge agreed that the question could be debated at trial but said it was irrelevant because of the Supreme Court’s ruling.

Ms. Schork filed a malpractice claim against the hospital with the Indiana Department of Insurance, and received what her lawyer described as a limited award; the amount was confidential. She said she could not continue to work at her supermarket job and is now unemployed.

Soon after Ms. Levine won her case, Ms. Schork wrote to congratulate her and to share her own story. At the bottom of the letter, Ms. Levine recalled, Ms. Schork apologized for her handwriting because she was writing with her left hand. “The fact that it had happened to her and she had this same struggle — and then to hear now that it’s getting dismissed — is just beyond me,” said Ms. Levine.

Ms. Schork said she and Ms. Levine later spoke on the telephone. “I’m glad for her,” she said, “but it didn’t help me any.”

Lawyers for generic drug companies say their clients are able to provide low-cost drugs because their primary task is replicating drugs. If the companies were expected to take responsibility for updating their labels, “we would effectively start to turn generic companies into brand companies, and of course the tremendous cost savings that American consumers have benefitted from would start to wane,” said Jay Lefkowitz, who served as the lead attorney representing generic companies before the Supreme Court.

The Supreme Court recognized that its decision must make “little sense” to plaintiffs who sue generic drug companies. However, Justice Clarence Thomas wrote for the court, “Congress and the F.D.A. retain the authority to change the law and regulations if they so desire.”

Some attorneys who follow the issue have speculated that Congress and the F.D.A. are reluctant to deal a blow to generic companies, which are responsible for providing cheap drugs to millions of American consumers, especially in an election year when health care is a hot issue.

In a statement last week, Representative Henry A. Waxman, Democrat of California, who co-wrote the Hatch-Waxman Act, said he was exploring ways to address the issue, either through legislation or a rule change.

Mr. Waxman argued in a brief opposing the generic companies in the Supreme Court case last year that Congress had never intended for generic companies to be freed of all responsibility. “Congress did not intend for consumers’ rights to be categorically eliminated simply because they purchased a generic rather than a brand-name drug,” he wrote.

Camille Baruch, 18, and her family say that is precisely what happened to her. When she was 12, Camille, of Rockville, Md., began taking the generic version of the antiacne drug Accutane and developed severe gastrointestinal pain several months later. Her diagnosis was ulcerative colitis, a type of inflammatory bowel disease, and she had to have her large intestine removed.

Six years and eight operations later, doctors have not been able to stabilize her condition. Her parents said the disease transformed their daughter from a talented basketball and softball athlete to someone who will struggle with debilitating physical challenges for the rest of her life.

Thousands of patients have sued Roche, the maker of Accutane, claiming that it caused their inflammatory bowel disease, and several have won multimillion-dollar verdicts against the company. In 2009, citing litigation costs and competition from generics, Roche removed Accutane from the market. In 2010, Camille sued the makers of the three generic versions of Accutane she took. Her lawyer, Tayjes Shah, said lawyers for the companies have told him they intend to ask for a dismissal. “I have very little optimism,” Mr. Shah said.

Camille, who was in the hospital this month recovering from another operation, said she had heard the arguments that the generic companies had made. “It makes me almost want to cry every time that I think that I took something that is nearly identical” to Accutane, yet she cannot sue, she said. “I lost everything. That is not a reason enough that these people aren’t to blame.”