ASHINGTON, May 24 - The Supreme Court agreed Monday to resolve an intensifying debate over whether states can prohibit out-of-state wineries from shipping directly to consumers. The eventual decision could have implications beyond wine sales for Internet commerce in general.

The appeals the justices accepted, from New York and Michigan, are among some two dozen cases now in courts around the country challenging laws that states defend as part of their authority to regulate the liquor industry but that small wineries and consumers have attacked as impermissibly protectionist.

The constitutional doctrines that undergird these positions are complex and contradictory. The 21st Amendment, which repealed Prohibition, gives states broad authority to regulate the sale and use of alcoholic beverages within their borders. But the Commerce Clause, as long interpreted by the Supreme Court, sharply limits the ability of individual states to erect economic barriers at their borders.

Not surprisingly, different courts have reconciled these competing doctrines in different ways, a circumstance that made the Supreme Court's intervention all but inevitable. The justices consolidated the cases for a single argument, to be heard late next fall.

In the Michigan case, the United States Court of Appeals for the Sixth Circuit, in Cincinnati, struck down the state's interstate-shipment ban last August on the ground that it amounted to unconstitutional discrimination against interstate commerce. Both the state government and the state's beer and wine wholesalers appealed to the Supreme Court; the cases are Granholm v. Heald, No. 03-1116, and Michigan Beer and Wine Wholesalers Association v. Heald, No. 03-1120.

The United States Court of Appeals for the Second Circuit, in Manhattan, upheld New York's law in a ruling three months ago. That court placed more emphasis on the state's 21st Amendment powers and found that the law was valid "within the ambit of that authority." The court said New York's law did not discriminate on its face because it permitted any winery with a "physical presence" in the state, such as an office, to ship directly to consumers.

Clint Bolick, strategic litigation counsel of the Institute for Justice, the libertarian public-interest law firm that brought the challenge to the New York law, said in an interview Monday that it was "ludicrous" to suppose that his client, Juanita Swedenburg, proprietor of a small Virginia vineyard, could open an office in New York or any other state.

"If you call her winery, she answers her own phone," Mr. Bolick said.

The appeal, filed on behalf of Ms. Swedenburg as well as a California winemaker named David Lucas and three New York wine consumers, is Swedenburg v. Kelly, No. 03-1274.

Mr. Bolick said a decision upholding the state laws could permit states to erect "serious barriers to e-commerce in general."

Viet D. Dinh, a law professor at Georgetown University who is representing the wholesale wine and liquor industry in defense of the state laws in these cases, said the Second Circuit's analysis in relying on the states' 21st Amendment authority was clearly correct. In an interview, Mr. Dinh, a former assistant attorney general, said that because alcohol was "unlike any other product," a decision upholding the state laws would not have implications for other types of commerce, on the Internet or elsewhere.

While direct sales from wineries to consumers are growing quickly as states relax their prohibitions or lose court cases, as Texas did last year, they are still a small portion of all wine sales, $200 million out of $18 billion last year. The stakes are obviously high, however, both to the wineries, which are motivated to avoid sharing their profits with wholesalers, and to the states. The National Conference of State Liquor Administrators estimated in 2000 that states were losing tens of millions of dollars in tax revenue from interstate wine sales to consumers. Thirty-six states have joined a brief filed by Ohio in support of Michigan's appeal.

New York's attorney general, Eliot Spitzer, filed a Supreme Court brief agreeing with Ms. Swedenburg that the court should hear the challenge to the New York law in order to clarify the national situation. He urged the court to uphold the law, however.

These were among other developments at the court on Monday:

Lethal Injection

The justices ruled unanimously that an inmate on Alabama's death row whose collapsed veins are not suitable for a lethal injection was entitled to bring a civil rights suit challenging, as cruel and unusual punishment, the state's plan to open a vein surgically in order to execute him.

As suggested by the unanimous vote on a court that is usually divided on criminal justice issues, Justice Sandra Day O'Connor's opinion in favor of the inmate, David L. Nelson, was a narrow one, confined to procedural issues and leaving the merits of the inmate's claim to be addressed by the lower federal courts.

State inmates are typically allowed only one petition for a writ of habeas corpus in federal court. One petition by Mr. Nelson, convicted of a 1977 murder, had already been rejected by the time he went to court to challenge the state's imminent plan to carry out his death sentence with a so-called "cut-down procedure," opening a two-inch cut in his arm to bypass veins that had collapsed from long-term drug use.

His new case was brought not as a habeas corpus petition but as a suit under the Civil Rights Act of 1871, a post-Civil War statute that permits suits for violations of constitutional rights. But the United States Court of Appeals for the 11th Circuit, in Atlanta, said the suit was functionally the same as a second habeas corpus petition and dismissed it.

Overturning that decision today, Justice O'Connor's opinion noted that Alabama had conceded that a prisoner who was not facing execution, but who needed medical treatment that required access to a vein, could sue to challenge the "cut-down procedure" as inadequate medical care.

"We see no reason on the face of the complaint to treat petitioner's claim differently solely because he has been condemned to die," Justice O'Connor said.

The case is Nelson v. Campbell, No. 03-6821.

Car Search

By a vote of 7 to 2, the court expanded the ability of the police to search the passenger compartment of a car in conjunction with the arrest of the driver or other occupant.

Previous decisions permitted officers, out of concern for their own safety, to conduct such searches if the occupant was inside the car when first stopped or contacted by the police. The question in the new case, Thornton v. United States, No. 03-5165, was whether the same rule applied if the occupant was outside the car at the time of the initial contact with the police.

The court's answer was yes, in an opinion by Chief Justice William H. Rehnquist that affirmed a ruling by the United States Court of Appeals for the Fourth Circuit, in Richmond, Va.

"The arrest of a suspect who is next to a vehicle presents identical concerns regarding officer safety and the destruction of evidence as the arrest of one who is inside the vehicle," the chief justice said, describing both settings as "highly volatile."

In this case, a man stopped by a Norfolk police officer for driving with a license tag that belonged to another car was found to have a handgun under the driver's seat. The man, Marcus Thornton, had parked his car and left it before the officer could pull him over.

While seven justices supported the result, Justices Antonin Scalia and Ruth Bader Ginsburg objected to the analysis and did not sign the majority opinion. They said the search could be seen as reasonable but could not be justified as a safety measure. Justices John Paul Stevens and David H. Souter dissented.