Immigrants convicted of minor drug offenses should not face automatic deportation, the Supreme Court ruled unanimously Monday, a decision that could allow thousands of legal immigrants the chance to argue for leniency from immigration judges.

The court overruled the legal interpretations of the federal government and a lower appeals court in saying that Jose Angel Carachuri-Rosendo should have had a chance to make his case for staying in the country.

Carachuri-Rosendo, a legal resident who had lived in the United States since he was 5, was deported to his native Mexico after being convicted of possessing a single tablet of Xanax, an anti-anxiety drug, and serving a 10-day sentence. He had been convicted of possessing a small amount of marijuana a year earlier and received a 20-day sentence.

In an opinion by Justice John Paul Stevens, the court said that was not what Congress had in mind when it mandated automatic deportation for any immigrant convicted of an aggravated felony. The government had said that Carachuri-Rosendo's second conviction put him in that category, even though local prosecutors did not increase the second offense to a drug-trafficking charge.

"We do not usually think of a 10-day sentence for the unauthorized possession of a trivial amount of a prescription drug as an 'aggravated felony,' " Stevens wrote. Immigrants who break the law should receive the chance to plead their case before an immigration judge rather than face automatic deportation, he said.

Manuel Vargas, senior counsel for the Immigrant Defense Project, said that would mean immigrants could ask a judge to consider factors such as their length of time in the United States, military service, and family and community ties. Illegal immigrants would still face virtually automatic deportation, he said.

Carachuri-Rosendo, who is in his early 30s, was deported even though his common-law wife, four children and other family members are U.S. citizens.

The case is Carachuri-Rosendo v. Holder.

The court also dealt second chances in another case.

It said a death-row inmate from Florida deserves another opportunity to have federal courts review his sentence because his lawyer did not meet a filing deadline.

The U.S. Court of Appeals for the 11th Circuit in Atlanta had ruled that even if Albert Holland's attorney Bradley M. Collins was "grossly negligent" in missing the deadline, the law didn't afford Holland, who was convicted of killing a police officer, another chance. Federal law requires that the lawyer must have exhibited "bad faith, dishonesty, divided loyalty, mental impairment or so forth" to file a petition after the deadline.

"In our view, this standard is too rigid," Justice Stephen G. Breyer wrote in the court's 7-2 opinion.

Breyer noted numerous examples of Holland's efforts to get the lawyer to file by the deadline and pointed out that in some cases, Holland's legal interpretations were right and Collins's were wrong. "The case before us does not involve, and we are not considering, a 'garden-variety claim' of attorney negligence," Breyer wrote.

Justices Antonin Scalia and Clarence Thomas dissented. Scalia said that although the court's "impulse to intervene when a litigant's lawyer had made mistakes is understandable," precedent demands a finding that the petitioner is "out of luck."

The case is Holland v. Florida.

The court also accepted California Gov. Arnold Schwarzenegger's challenge of a special federal judicial panel's decision that the state must reduce its prison population by 46,000 inmates over the next two years. The court will hear the case in the term that begins in the fall, and the order is on hold until the justices decide the issue. The case is Schwarzenegger v. Plata.