The Supreme Court ruled yesterday that a noncitizen convicted of injuring two people while driving drunk cannot be deported as a violent criminal, in a unanimous decision that resolved a long-standing legal debate in favor of immigrants' rights.

Issuing his first written opinion since the court announced Oct. 25 that he has thyroid cancer, Chief Justice William H. Rehnquist wrote that drunken driving, even when it results in serious harm to others, does not entail the kind of specific criminal intent that Congress meant to punish when it passed a law in 1996 requiring the removal of all immigrants who commit "crimes of violence."

"Interpreting [the law] to encompass accidental or negligent conduct would blur the distinction between the 'violent' crimes Congress sought to distinguish for heightened punishment and other crimes," Rehnquist wrote.

The court ruled in favor of Josue Leocal, 47, a Haitian immigrant who came to the United States in 1980 and became a legal resident in 1987 but was ordered deported in October 2001 after pleading guilty in Florida to two counts of causing serious bodily injury while driving under the influence of alcohol. In November 2002, after serving his sentence for the crimes, Leocal was deported to Haiti.

Last year, the Atlanta-based U.S. Court of Appeals for the 11th Circuit upheld his deportation; yesterday's Supreme Court ruling overturns that opinion and opens the door for the readmission of Leocal, whose wife and two children are U.S. citizens.

It is a defeat for the Bush administration, which had argued that drunken driving could be considered a crime of violence because even the unintentional use of force, as in the wild maneuvers of an intoxicated driver, could be construed as violence.

"Today's unanimous decision repudiates the administration's improper interpretation of the law and underscores the crucial role of the courts in reviewing government deportation orders," said Lucas Guttentag, director of the American Civil Liberties Union's Immigrants Rights Project. "It is now incumbent on the government to allow immigrants who have been wrongly deported to return."

Immigrants rights groups estimate that hundreds of noncitizens may have been deported for drunken-driving offenses since 1996, when the Clinton administration first made the argument that such felonies should be considered deportable crimes.

In 1998, during Operation Last Call in Texas, immigration agents rounded up hundreds of noncitizens with drunken-driving convictions, including some cases that were many years old.

The Bush administration adopted the Clinton interpretation of the law, even as several lower courts rejected it, leaving the law in an unsettled state until yesterday.

Rehnquist did not appear at the bench to read the 101/2-page opinion. It was announced in his absence by John Paul Stevens, the senior associate justice.

It was the fifth straight oral argument session that Rehnquist has missed since not appearing in court Nov. 1, the date on which he had initially hoped to return after undergoing cancer-related throat surgery Oct. 23.

Leocal v. Ashcroft, No. 03-583, was argued before the court Oct. 12, with Rehnquist presiding.

That week, Rehnquist had an MRI test on his throat -- and he has apparently been under the care of physicians almost continuously since. In a Nov. 1 statement, he said he is undergoing radiation and chemotherapy treatments.

The court has not confirmed the precise nature of Rehnquist's illness. Outside experts have said that, based on the course of his treatment so far, it is likely that he has a very aggressive and often fatal disease called anaplastic thyroid cancer.