Immigrants who are convicted of minor marijuana offenses are not subject to mandatory deportation, the Supreme Court ruled Tuesday.

Those whose crime amounts to a “social sharing of a small amount of marijuana” should be able to at least ask the attorney general to spare them automatic deportation, the court ruled 7 to 2.

The court sided with Adrian Moncrieffe, who came to the United States legally from Jamaica in 1984 when he was 3 years old. Although the amount of marijuana found during a 2007 traffic stop in Georgia was equivalent to two to three marijuana cigarettes, federal authorities decided to deport him.

But Justice Sonia Sotomayor said his crime should not have been considered among the charges of illicit drug trafficking for which deportation is mandatory.

She said it would have to be shown that Moncrieffe had a larger amount of marijuana or that he intended to sell it for such a penalty to be triggered.

She was joined by Chief Justice John G. Roberts Jr. and Justices Antonin Scalia, Anthony M. Kennedy, Ruth Bader Ginsburg, Stephen G. Breyer and Elena Kagan.

Sotomayor criticized the government for doling out such tough penalties.

“This is the third time in seven years that we have considered whether the government has properly characterized a low-level drug offense as ‘illicit trafficking in a controlled substance,’ and thus an ‘aggravated felony,’ ” Sotomayor wrote. “Once again we hold that the government’s approach defies the commonsense conception of these terms.”

In Moncrieffe’s case, he pleaded guilty to possession of marijuana with intent to distribute. As a first-time offender, the Georgia court withheld a judgment of conviction and jail time, and said that after five years of probation, the charge would be expunged.

Nevertheless, an immigration judge agreed with the government that possession with intention to distribute was equivalent to a felony under federal law, and Moncrieffe was deported to Jamaica. The U.S. Court of Appeals for the 5th Circuit agreed.

With the Supreme Court decision, Moncrieffe should be allowed to appeal the deportation.

Justices Clarence Thomas and Samuel A. Alito Jr. dissented. Thomas said the decision conflicted with a “plain reading” of the federal statute and noted he had dissented in the two previous cases Sotomayor mentioned.

Alito said the court’s decision will mean that because of the way some states’ laws are written, an alien “convicted of possessing tons of marijuana with the intent to distribute” would be eligible to appeal deportation.

Sotomayor said Alito’s worry about international drug dealers was overblown.

“The Attorney General may, in his discretion, deny relief if he finds that the noncitizen is actually a member of one ‘of the world’s most dangerous drug cartels’ . . . just as he may deny relief if he concludes the negative equities outweigh the positive equities of the noncitizen’s case for other reasons,” she wrote.

The case is Moncrieffe v. Holder .

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