The Supreme Court made it easier yesterday for police to crack down on pornographic videocassette dealers, ruling 6 to 3 that the First Amendment does not place special restraints on police seeking a warrant to seize such materials.

Justice William H. Rehnquist, writing for the majority, said that police asking for a warrant to seize obscene materials need only to meet the same legal standards of proof for warrants that must be met when police try to seize drugs or weapons.

In other decisions yesterday, the court made it more difficult for tax-exempt professional groups to avoid paying taxes on profits from advertising in their magazines and set aside a $3.5 million damage award against Aetna Life Insurance Co. in Alabama because a state supreme court judge ruling in the case had a "direct and substantial" financial interest in the outcome.

The obscenity ruling overturned one by the Court of Appeals of New York, which had dismissed obscenity charges against a video store near Buffalo. The appeals court said that the warrants allowing the seizure of films such as "Debbie Does Dallas" and "Taboo" were based on inadequate information. The lower court said that First Amendment free speech guarantees require judges to hold police to "a higher standard for evaluation of a warrant application" for the seizure of books and films than for the seizure of other materials, such as weapons or drugs.

But Rehnquist said the high court has "never held or said that such a 'higher' standard is required by the First Amendment." Rehnquist said "the longstanding special protections" in prior court decisions to safeguard free speech rights "are adequate to ensure that First Amendment interests will not be impaired."

Justice Thurgood Marshall, joined by Justices William J. Brennan and John Paul Stevens, dissented in New York v. P.J. Video Inc. Marshall said that the majority should have deferred to the judgment of the state courts, noting that they relied on numerous Supreme Court rulings calling for "scrupulous exactitude" in reviewing warrant requests involving books or films.

Marshall said the affidavits describing the films accompanying the warrant request in yesterday's case were "mere listings of selected scenes from the films that involved depictions of sex" and that such listings could easily be used to describe films such as "Last Tango in Paris" or "Clockwork Orange," which have recognized merit.

In the tax case, U.S. v. American College of Physicians, the court made it difficult, although not impossible, for hundreds of tax-exempt educational, scientific or charitable organizations to avoid paying tens of millions of dollars in taxes that the Internal Revenue Service says they owe for profits from advertising in their journals.

Marshall, writing for a unanimous court, rejected the government's contention that federal law requires a blanket rule that income from magazine advertising is always taxable. Marshall said that if the advertising was tightly controlled to "contribute importantly" to educational purposes, perhaps the revenue could be exempt.

John B. Huffaker, an attorney for the American College of Physicians, which asked for a refund of the taxes it had paid on profits from its journal, said that Marshall left the "door barely, barely, barely ajar. But I don't think there is a publication in this country that meets this standard."

In the third case, Aetna v. Lavoie, the court, in a unanimous opinion by Chief Justice Warren E. Burger, focused on the participation of Alabama Supreme Court Justice T. Eric Embry in a case involving a suit against an insurance company.

Burger said Embry wrote a 5-4 decision in that case upholding the largest punitive damages award ever issued in Alabama, while at the same time he was suing another insurance company on similar grounds.

"Thus, his opinion for the Alabama Supreme Court had the clear and immediate effect of enhancing both the legal status and the settlement value of his own case," Burger said.

"We conclude that Justice Embry's participation in this case violated [the Lavoies'] due process rights," Burger said, sending the case back for lower court review. Embry, who settled his insurance claim for $30,000, retired last year from the state court for health reasons, Burger said.

While Burger emphasized the fact that Embry wrote the majority opinion in the case, Justice Harry A. Blackmun, concurring in the ruling, emphasized that it did not matter which side Embry might have been on.

Embry's "mere participation in the shared enterprise of . . . decision-making" Blackmun said, was enough to throw out the state court ruling. "We do know, from our own experience on this nine-member court, that a forceful dissent may lead justices to rethink their original position and change their votes."

Blackmun said that "our experience should tell us that the concessions extracted as the price of joining an opinion may influence its shape as decisively as the sentiments of the nominal author."