The Supreme Court on Thursday ruled against an undocumented immigrant who sought to challenge his removal from the U.S. after being convicted in Nebraska of using a false identity to gain employment. 

In a 5-3 ruling that broke along ideological lines, the court’s conservative majority ruled that Clemente Pereida’s crime made him eligible for deportation, despite some uncertainty about which exact provision of the state criminal code he had violated.

Pereida’s ability to remain in the U.S., where he has lived for 25 years, hinged on whether his use of a fraudulent social security card to obtain a job was considered to be a crime of “moral turpitude,” or a serious offense. Such convictions make it vastly more difficult for undocumented immigrants to challenge their removal by immigration authorities.

The narrow issue before the justices was which party — the defendant or the government — bears the burden of proving whether or not the crime in question was one of moral turpitude when the factual record is unclear. 

Five conservative justices on Thursday ruled that the burden lies with the defendant, prompting a dissent from the court’s three liberals. Justice Amy Coney Barrett, the court's sixth conservative member, had not been seated when the case was argued in October.

Justice Neil Gorsuch, writing for the majority, said federal immigration law imposes a “heavy burden” on immigrants seeking relief from deportation. 

“That includes proving they do not stand convicted of a disqualifying criminal offense,” Gorsuch, a Trump appointee, wrote. 

In dissent, Justice Stephen Breyer wrote that the ambiguity over which provision of the state criminal code was violated should favor the defendant. The Nebraska law in question contained both serious offenses and more minor ones.

“The relevant documents in this case do not show that the previous conviction at issue necessarily was for a crime involving moral turpitude,” Breyer wrote. His dissent was joined by fellow liberal justices Elena Kagan and Sonia Sotomayor.

Kevin Johnson, dean of the University of California Davis School of Law, said it appeared “somewhat unfair and inconsistent” that a long-term resident would be removed from the U.S. without the court knowing the precise details of his conviction.

But the decision could lead to improvements in legal advocacy for undocumented immigrants, he said. Defense lawyers who strike plea deals with prosecutors on behalf of clients may now pay closer attention to possible immigration repercussions.

“For criminal lawyers, there’s going to be a fairly heavy burden on them to know the immigration consequences of criminal conviction,” Johnson said. “Hopefully it will get them to pay more attention to the basis for criminal conviction to try to protect their clients from getting deported.”

Updated at 1:25 p.m.