Prosecutors can use statements made by victims to 911 operators or police during emergencies if the victims do not testify at trial, the Supreme Court ruled in a pair of cases Monday.

In a case out of Washington state, justices voted 9-0 that a defendant's right to confront his accuser was not violated because he could not cross-examine a woman who claimed in a 911 call that he had assaulted her.

By an 8-1 vote in a second case, the court ruled that a police officer had crossed the line — from dealing with an emergency to conducting an investigation — when he questioned an Indiana woman about what her husband had done to her well after the assault had taken place.

Justice Clarence Thomas was the lone dissent in the Indiana case, writing that he believed the officer's testimony about what the woman had told him was admissible in court.

Writing for the majority, Justice Antonin Scalia said 911 statements can be powerful evidence because they often are made during emergencies. Such evidence can have a profound effect on jurors, increasing chances of convictions for defendants who cannot question the witnesses, he said.

But Scalia said a line must be drawn on when such evidence can be used.

The evidence is admissible in court when police are trying to deal with an emergency, such as domestic violence, he wrote. But such statements cannot be used if the emergency has ended and police are gathering evidence to use in filing criminal charges, Scalia said.

In court filings, women's groups argued that judges need to be flexible in dealing with testimony in domestic violence cases because victims or key witnesses are not willing or not available to testify.

Scalia said he tended to agree. "This particular type of crime is notoriously susceptible to intimidation or coercion of the victim to ensure that she does not testify at trial," he wrote. "When this occurs, (it) gives the criminal a windfall."

But Scalia said that doesn't mean a defendant's rights to confront an accuser can be set aside. Instead, he urged prosecutors to offer evidence at trial that a defendant intimidated the witness into silence and "forfeited" his right to confront his accuser.

The cases involved Adrian Davis of Washington and Hershel Hammon of Indiana who had argued their rights were violated because their accusers did not testify under oath and were not subjected to cross-examination at their trials.

Lawyers on all sides of the cases — as well as the Bush administration — wanted the justices to clarify a 2004 high court decision that barred prosecutors' use of statements from victims or witnesses if a defendant did not have a chance to question them in court.

At Davis' trial, a judge allowed the tape of Michelle McCottry's February 2001 emergency call to be admitted into evidence but barred police testimony about what McCottry had said to officers. She disappeared before trial and did not testify despite a subpoena.

In the other case out of Peru, Ind., Amy Hammon also did not testify. But a judge allowed a police officer to testify that she had told him that her husband, Hershel, had thrown her into the glass panel of a gas heater during an argument before police arrived.

Thomas, in his dissent, said the police officer's questions could have been posed to determine whether Amy Hammon remained in danger, not solely to gather evidence to charge her husband with a crime.

The cases are Davis v. Washington, 05-5224, and Hammon v. Indiana, 05-5705.