The Supreme Court on Tuesday increased the chances for some immigrants to remain in the United States if they have been convicted of drug possession under state laws.

The justices' 8-1 ruling came on the same day the court heard arguments in another immigrant case in which a man in California is trying to avoid deportation after pleading guilty to a theft charge.

The ruling came in the case of Jose Antonio Lopez, a 16-year permanent U.S. resident who pleaded guilty to telling someone where to obtain cocaine.

The crime, aiding and abetting possession of drugs, is a felony in South Dakota. Most first-time simple possession offenses are punished as misdemeanors under the federal Controlled Substances Act.

Conduct that is a felony under state law but a misdemeanor under the Controlled Substances Act is not an aggravated felony for purposes of immigration, Justice David Souter wrote.

Lopez was deported to Mexico in January 2006, but will come back to the United States where an immigration judge will decide whether he may remain in the country.

He wants to return to his family in the United States who include his 11-year-old son and 6-year-old daughter, and his legal prospects have improved greatly because of the court ruling, his lawyers said.

Lopez, who had operated a grocery store in Sioux Falls, S.D., still could face deportation, but an immigration judge would have discretion to allow him to remain in the United States.

In opposing the immigrant's legal position, the Bush administration said that Congress left the door open to counting state felonies under the federal Controlled Substances Act. That would trigger deportation under the Immigration and Nationality Act.

Reading the law "the government's way ... would often turn simple possession into trafficking, just what the English language tells us not to expect and that result makes us very wary of the government's position," Souter wrote. Justice Clarence Thomas dissented, declaring his colleagues' approach "unpersuasive."

After the justices issued the decision, they turned to the case of Luis Alexander Duenas-Alvarez, a Peruvian immigrant in California who pleaded guilty to unlawfully taking a car, prompting the government to file removal proceedings against him.

The 9th U.S. Circuit Court of Appeals ruled that Duenas-Alvarez's conviction did not qualify as an aggravated felony under immigration law. The federal government appealed to the Supreme Court.

In other action, the court dismissed the case of a third immigrant, whose case had been consolidated with that of Lopez. The court said its decision to accept the case of Reymundo Toledo-Flores had been improvidently granted.

Toledo-Flores is a Mexican national who objected to having his latest conviction for illegally entering the United States classified an aggravated felony. Toledo-Flores was contesting his prison term, not his deportation, and he had already served it.

The cases are Lopez v. Gonzales, 05-7664, and Toledo-Flores v. U.S., 05-493.