WASHINGTON (Reuters) - The U.S. Supreme Court on Tuesday ruled that a Mexican immigrant convicted of consensual sex with his under-age girlfriend was not eligible to be deported in a decision issued at a time when President Donald Trump is moving to increase deportations.

Taking the same stance in the case as the Obama administration previously had, the Trump administration argued that Juan Esquivel-Quintana, who was a lawful permanent U.S. resident who came to the country at age 12, should have been subject to deportation as a result of the conviction.

The justices disagreed on an 8-0 vote, finding that for the purposes of immigration law a minor must be under 16 for the crime to be deemed serious enough to lead to deportation.

Esquivel-Quintana was arrested in 2009 and convicted under California law for having sex with his 16-year-old girlfriend when he was 20 and 21 years old. The California law says it is a criminal offense for an adult to have sex with anyone under 18 when the age difference between the two is more than three years. Six other states have similar laws.

Federal immigration law says any immigrant convicted of “sexual abuse of a minor” can be deported.

Esquivel-Quintana has since moved to Mexico but could now return to the United States as a result of the ruling, said his lawyer, Jeffrey Fisher.

Writing for the court, Justice Clarence Thomas wrote that “the generic federal definition of sexual abuse of a minor requires that the victim be younger than 16.”

The justices reversed a January 2016 ruling by the Cincinnati-based 6th U.S. Circuit Court of Appeals in favor of the government. The appeals court had deferred to the interpretation of the law embraced by the Board of Immigration Appeals, which also ruled against Esquivel-Quintana.

Trump’s appointee the Supreme Court, Justice Neil Gorsuch, was not on the court when the case was argued and did not participate in the ruling.

The Trump administration has announced plans to increase deportations and broaden the categories of immigrants targeted. The administration said on Friday it would ask the Supreme Court to revive Trump’s travel ban on people entering the United States from six predominantly Muslim countries, which has been blocked by lower courts.