ASHINGTON, June 16 — The Supreme Court today upheld the longstanding ban on direct corporate contributions to candidates in federal elections, refusing by a vote of 7 to 2 to create an exception permitting unlimited contributions by corporations organized for the purpose of ideological advocacy.

The case was not directly related to the constitutional challenge and defense of the new campaign finance law, which the court is to hear on Sept. 8. The new law, while placing significant restrictions on corporations, did not change the existing requirement that any corporation campaign contributions be made through a political action committee, subject to limitations and disclosure requirements, rather than directly from corporate treasuries.

Nonetheless, some election law experts, particularly those who support the Bipartisan Campaign Reform Act, more commonly known as the McCain-Feingold law after its chief Senate sponsors, were quick to derive encouragement from today's ruling. Justice David H. Souter's majority opinion repeatedly emphasized the need for "deference to legislative choice" in campaign finance, and endorsed several rationales for the close regulation of corporate political money in particular.

The decision overturned a ruling by the federal appeals court in Richmond, Va., holding that the ban on direct contributions contained in the Federal Election Campaign Act of 1971 was unconstitutional as applied to a nonprofit anti-abortion group, North Carolina Right to Life Inc. While organized as a corporation, it has no shareholders and exists for the purposes of counseling pregnant women on alternatives to abortion and advocating for its agenda. It brought a First Amendment challenge to the contribution ban, based largely on a 1986 Supreme Court decision holding that organizations of this type could not be restricted in campaign expenditures.

In the decision today, Federal Election Commission v. Beaumont, No. 02-403, the majority made it clear that it had no interest in revisiting the constitutional distinction between contributions and expenditures that the court established in 1976 in the Buckley v. Valeo decision. That landmark ruling gave expenditures the highest possible First Amendment protection, striking down spending limits while upholding limits on contributions.

In describing the state of the law, Justice Souter said, "Restrictions on political contributions have been treated as merely `marginal' speech restrictions subject to relatively complaisant review under the First Amendment, because contributions lie closer to the edges than to the core of political expression." He added, "Within the realm of contributions generally, corporate contributions are furthest from the core of political expression, since corporations' First Amendment speech and association interests are derived largely from those of their members."

Richard Hasen, an election law expert at Loyola Law School in Los Angeles, said the court's approach boded well for the two main provisions of the new campaign finance law: restrictions on corporate spending for issue advertisements, and a ban on receipt by the political parties of unregulated "soft money" contributions from corporations and labor unions.

Although those provisions were not before the court, Professor Hasen said, "it's the tone here that's notable, the deference to Congress, the emphasis on the dangers of the corporate war chest."

The two dissenters, Justices Clarence Thomas and Antonin Scalia, provided no surprise in stating their longstanding view that contributions, as well as expenditures, were subject to the strictest constitutional scrutiny. The challenged provision could not survive that rigorous review, they said in an opinion by Justice Thomas.

Another campaign regulation skeptic, Justice Anthony M. Kennedy, concurred with the majority in a separate opinion but did not sign Justice Souter's opinion for the court. The court's precedents on corporate contributions supported the result, he said. But he added, "Were we presented with a case in which the distinction between contributions and expenditures under the whole scheme of campaign finance regulation were under review, I might join Justice Thomas's opinion."

Justice Souter's majority opinion emphasized the deep roots of the federal ban on direct corporate political contributions, dating to the first federal campaign law, passed in 1907. "Not only has the original ban on direct corporate contributions endured, but so have the original rationales for the law," Justice Souter said. He continued: "In barring corporate earnings from conversion into political `war chests,' the ban was and is intended to prevent corruption or the appearance of corruption."

In addition, he said, in the absence of restrictions, those who control corporations "could exceed the bounds imposed on their own contributions by diverting money through the corporation." He said the court could not rule for North Carolina Right to Life in this case "without recasting our understanding of the risks of harm posed by corporate political contributions, of the expressive significance of contributions, and of the consequent deference owed to legislative judgments on what to do about them."

There were also these developments at the Supreme Court today:

Prison Visits

A 9-to-0 decision upheld restrictions imposed by Michigan four years ago on the rights of prison inmates to receive visits from family members and acquaintances. The list of visitors is limited to immediate family members, including children and siblings but not nieces and nephews who are younger than 18. Children must be accompanied by an adult who is a family member or the child's legal guardian. Ten nonfamily members may be included on the approved visitor list.

In addition, an inmate who has committed two violations of the prison's drug or alcohol rules loses the right to receive any visits except from lawyers or members of the clergy for at least two years, with reinstatement after that at the discretion of the warden. At least 14 other states, including New York, remove or restrict visiting privileges from inmates who commit drug infractions.

The Michigan regulations apply to noncontact visits, during which the prisoner and visitor communicate through a glass panel. A group of inmates and family members brought a class-action lawsuit that challenged the regulations on the basis of the First Amendment right to freedom of association and the Eighth Amendment prohibition of cruel and unusual punishment.

Both the Federal District Court in Detroit and the United States Court of Appeals for the Sixth Circuit, in Cincinnati, declared the regulations unconstitutional. They "fall below minimum standards of decency owed by a civilized society to those who it has incarcerated," Judge Gilbert S. Merritt wrote for the three-judge Sixth Circuit panel.

In Michigan's appeal, Overton v. Bazzetta, No. 02-94, all nine justices disagreed with the lower courts. Writing for himself and six others, Justice Kennedy said that while the regulations, particularly the two-year ban on visits, were "severe," they bore "a rational relation to legitimate penological interests" and did not fall below minimum constitutional standards. Justices Thomas and Scalia concurred separately in an opinion by Justice Thomas that reiterated his longstanding view that the Eighth Amendment applies only to types of punishment and not to particular conditions of confinement.

Trespass

The court unanimously overturned a Virginia Supreme Court decision that had declared unconstitutional a public access policy at a Richmond housing project. The city had privatized the project's streets, putting them off limits to nonresidents under a regulation that made anyone who returned after having once been sent away subject to prosecution for trespass.

The Virginia court found the policy invalid under the First Amendment, declaring that it was so broad as to deter protected speech and that it left too much enforcement discretion in the hands of the project's manager.

But the man who challenged the policy, Kevin L. Hicks, said he was visiting his mother and his children and did not claim that he was engaged in protected First Amendment activity. Writing for the court today in Virginia v. Hicks, No. 02-371, Justice Scalia said that what is known as the "First Amendment overbreadth doctrine" should not be applied to bar all enforcement of a law restricting only a small proportion of speech "relative to the scope of the law's plainly legitimate applications."

Justice Scalia said a new First Amendment challenge to the policy could be brought by anyone whose speech was actually restricted.