(Reuters) - The U.S. Supreme Court during oral arguments on Tuesday sounded divided over whether a Mexican citizen could be prosecuted for illegally reentering the U.S. after being deported more than two decades ago, even though his removal based on a DUI conviction was no longer valid.

The court's liberal wing – Justices Stephen Breyer, Sonia Sotomayor and Elena Kagan – signaled their agreement with Bradley Garcia of O'Melveny & Myers that his client, Refugio Palomar-Santiago, could not be convicted of unlawful reentry after the Supreme Court in 2004 held that DUI was not an aggravated felony that could subject a non-citizen to deportation.

Breyer told Assistant Solicitor General Erica Ross that it would be "anomalous" to allow a federal prisoner convicted of a crime that is later ruled unconstitutional to seek release by filing a habeas corpus petition, but not to afford the same kind of relief to non-citizens charged with illegal reentry.

Ross responded that those circumstances are distinct because habeas proceedings involve claims of actual innocence, and Palomar-Santiago does not contend that he entered the U.S. legally prior to his 2018 arrest.

Ross told the justices that federal law only allows defendants charged with illegal reentry to challenge deportation orders if they can first show that they exhausted administrative options, such as reopening their removal cases or appealing to the Board of Immigration Appeals (BIA), and that they were deprived of an opportunity for judicial review.

But Garcia said those conditions only apply when a defendant is seeking to prove that an underlying deportation was invalid. Palomar-Santiago's 1998 deportation was indisputably invalid after the high court's ruling six years later in Leocal v. Ashcroft, Garcia said.

Justice Samuel Alito sounded unconvinced, saying that even if Palomar-Santiago had an "open and shut" argument about the validity of his deportation, that still amounted to a challenge. Garcia countered that he was challenging "the government's use of the order," and not the order itself.

Garcia also told the court that, like the vast majority of individuals who appear in immigration court without lawyers, Palomar-Santiago never had a meaningful opportunity to challenge his removal. He would have had to convince the BIA to reverse its longstanding position that DUI was an aggravated felony, which did not happen until the Supreme Court took up the matter several years later in Leocal, Garcia said.

Palomar-Santiago returned to the U.S. in 2017 and was charged with illegal reentry, but a federal judge in California dismissed the indictment. The judge cited 9th U.S. Circuit Court of Appeals precedent that said individuals can only be convicted of illegal reentry if the underlying deportation was valid.

The government appealed, urging the 9th Circuit to reconsider its prior holdings. But a three-judge panel last year said it was bound by those decisions, and upheld the dismissal of the indictment.

Ross on Tuesday told the Supreme Court that Palomar-Santiago could have asked the BIA to review his deportation order after it was issued, and he could have moved to reopen his case after the Supreme Court decided Leocal.

"But he could not simply enter the country and claim immunity from prosecution," she said.

The case is United States v. Palomar-Santiago, U.S. Supreme Court, No. 20-437.

For the government: Assistant Solicitor General Erica Ross

For Palomar-Santiago: Bradley Garcia of O'Melveny & Myers