A judge in Boston has found a U.S. Immigration and Customs Enforcement (ICE) agent in contempt after he detained a suspect while the man was on trial.

ICE agent Brian Sullivan apprehended Wilson Martell-Lebron last week as he was leaving the courthouse. However, a Boston Municipal Court judge ruled on Monday that Sullivan had violated Martell-Lebron’s rights to due process and a fair trial by taking him into custody during the proceedings, the Associated Press reported.

“It’s a case of violating a defendant’s right to present at trial and confront witnesses against him,” Judge Mark Summerville said from the bench. “It couldn’t be more serious.”

Summerville dismissed the charge against Martell-Lebron for making false statements on his driver’s license application—specifically, claiming he wasn’t Martell-Lebron, the report said. Following this action, the judge filed the contempt charge against Sullivan, which may prompt Suffolk County District Attorney Kevin Hayden to review the case and decide whether any charges should be pursued.

“It’s reprehensible,” Ryan Sullivan, one of Martell-Lebron’s lawyers said. “Law enforcement agents have a job to see justice is done. Prosecutors have a job to see justice is done. There is no greater injustice in my mind than the government arresting someone, without identifying themselves, and preventing them from exercising their constitutionally guaranteed right to a jury trial.”

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The incident is the latest as federal immigration agents target the Boston area in search of people in the country illegally. Boston has declared itself a “sanctuary city” for illegal aliens, meaning city officials have barred local police from assisting federal immigration officers

President Donald Trump’s border czar Tom Homan and Republicans in Congress have criticized the city for not cooperating in deporting individuals charged with violent crimes. Mayor Michelle Wu, a Democrat running for reelection this year, stated that she wants Boston to remain a welcoming place for immigrants, emphasizing that city policies are designed to limit cooperation with immigration enforcement, the AP said.

Sullivan described a tense situation in which ICE agents quickly apprehended Martell-Lebron without identifying themselves, then placed him into a pickup truck and drove off. The trial had just started, with opening statements and the first witnesses.

Sullivan added that Martell-Lebron, a Dominican Republic native living with family in Massachusetts, is now being held at the Plymouth detention facility for allegedly being an undocumented immigrant, the AP noted.

“What we were challenging is that they arrested him in the middle of his trial and did not return him,” he told the outlet. “If he had been brought to court on Friday morning by ICE, we would not have moved to dismiss. We would not be asking for sanctions.