WASHINGTON – The Supreme Court yesterday scrutinized a New York law that prevents out-of-state wineries from shipping directly to consumers, in a case that could affect Internet wine commerce nationwide.

California and Virginia wineries and three oenophiles have challenged the law, and a similar Michigan statute, for discriminating against out-of-state businesses. Federal appeals courts have reached conflicting conclusions about the bans.

Yesterday, the justices questioned whether the law served any purpose other than protecting the profits of instate businesses – a rationale that the court has held in the past to be insufficient to justify discrimination against out-of-state suppliers.

A lawyer for New York, Caitlin Halligan, told the justices that the ban was necessary to prevent the shipping of alcohol to minors, and to enable the state to collect taxes in light of a congressional moratorium on taxes of products shipped across state lines.

New York’s position was bolstered by written briefs from more than 30 states, as well as from as religious, educational, and traffic-safety groups, among others.

But the judges took a critical view of the states’ arguments that the ban is justified for reasons other than protectionism.

Justice Souter noted that despite concerns about shipping to minors, local companies were already free to ship directly to consumers.

“The very activity you don’t want to engage in, your wineries are engaging in,” he told the lawyer for Michigan, Thomas Casey.

Several judges also saw an inconsistency in New York’s argument, given that the law does allow out-of-state wineries to ship directly to homes if they set up a distribution warehouse and office within the state.

Justice Scalia asked Ms. Halligan how the existence of an office inside New York would prevent the sale of wine to minors or the avoidance of taxes. Before she could respond, the justice answered his own question, stating, “It can’t prevent it at all.”

Ms. Halligan countered that the law provides a “powerful deterrent” to scofflaws who risk losing their New York licenses and enables local law enforcement to better detect illegal activity. Sending inspectors to California would be “completely unfeasible” she said.

But Justice Stevens asked why wineries could not make their records available to New York auditors over the Internet, and why they could not be licensed under the condition that they submit to New York’s tax jurisdiction.

Ms. Halligan argued that the in-state requirement enables state inspectors to arrive on the premises of wineries to physically count the bottles on the shelves to see if their numbers match those in the records. But she conceded when pressed by a justice that there is “not clear evidence” in the court record as to whether such inspections take place.

At one point, Justice Ginsburg reminded Ms. Halligan that a New York lawyer had conceded earlier in the litigation that the law had been designed primarily to protect local wineries – a comment that Ms. Halligan dismissed as “an off-the-cuff remark by a single attorney.”

A lawyer for the wineries, Clint Bollick, told the court, “This is market foreclosure, pure and simple.”

Mr. Bollick, who is an attorney with a civil liberties law firm, the Institute for Justice, said the case is the first to test the vitality of constitutional guarantees of interstate commerce in the Internet era.

The case requires the justices to reconcile two parts of the Constitution that appear in conflict: a section of the post-Prohibition 21st Amendment, which granted states control over liquor regulation, and the Commerce Clause, which gives the federal government the power to regulate interstate commerce.

Justices Ginsburg and O’Connor were among the justices who noted that the Supreme Court already held, in a 1984 case known as Bacchus Imports v. Dias, that the 21st Amendment did not give states the power to levy a discriminatory tax against out-of-state distributors merely for protectionist reasons.

Three members of the current court – Justices O’Connor, Rehnquist, and Stevens – were among the dissenters in that case. But Justice O’Connor told the states’ lawyers that the case “cuts against” them and did not signal any intention to overrule the decision.

Chief Justice Rehnquist, who is receiving treatment for thyroid cancer, did not attend the argument.

The New York case is on appeal from the U.S. Court of Appeals for the 2nd Circuit, which upheld the ban on the grounds that an out-of-state winery can become a New York winery by opening a warehouse and a separate office in New York.

The Michigan law, in contrast, was struck down by the 6th Circuit as excessively protectionist.

After the hearing, the lead plaintiff, Juanita Swedenburg, a Northern Virginia vintner who has been blocked from the New York State market, said that “the important thing to me is to be able to service our customers.”

Mr. Casey told reporters after the hearing that a loss for the states would mean “the end of the entire alcohol regulation system in this country.” Citing the “evils inherent in the consumption and distribution of alcohol,” he said a “better solution,” should the court find discrimination in the law, would be for states to ban all direct shipments of alcohol to consumers, rather than allow all shipments in.

A decision in the case is expect before the end of June.