WASHINGTON, D.C. — The Supreme Court on Tuesday strengthened the Trump administration’s power to hold immigrants in jail for months or years as they fight deportation, ruling federal law gives these detainees no right to a bail hearing nor a chance to go free.

In the 5-3 decision, the court’s majority found that federal law says immigrants who face deportation “shall be detained” while their cases are being considered. The court’s conservatives rejected the view of federal judges in California who said detained immigrants have a right to a bail hearing after six months in jail.

The ruling is a setback, but not a final defeat, for immigrants’ rights activists in Los Angeles who brought a class-action suit on behalf of tens of thousands of non-citizens who are arrested and held for possible deportation. They include people who seek asylum because they fled persecution as well as people who have a lawful status here but were arrested because they had a crime on their records.

Many of these immigrants eventually win their cases, but only after they have spent a year or more in jail. The 9th Circuit Court of Appeals decided they should have a hearing after six months and a right to go free if they could show they were not a danger to the community or likely to flee.

The case of Jennings v. Rodriguez began in lower courts a decade ago, before Barack Obama was elected president. It was first argued at the high court in November 2016, a few weeks after Donald Trump won election. Trump’s campaign pledge to round up and deport more immigrants had raised the stakes in the case.

At the end of the last term, the court said it would rehear the case in the current term, presumably to allow the newly arrived Justice Neil M. Gorsuch to cast a vote.

Even after an unusually long time to reach a decision, the court issued only a partial ruling.

Justice Samuel A. Alito Jr., speaking for the high court, said the federal immigration law does not call for bail hearings, and the 9th Circuit had no authority to order them.

However, the justices did not rule on whether the Constitution gives detained immigrants a right to a hearing, and it sent the case back to California for that issue to be decided.

Justice Stephen Breyer read his dissent in court and said the ruling would affect thousands of people in jail “who believe they have a right to enter or remain in the United States. … This court, I think for first time ever, reads a statute as permitting long-term confinement of a ‘person’ in the United States without an opportunity to obtain bail.”

As he noted, the Constitution says no person “shall be deprived of life, liberty or property without due process of law,” and the word “person” has been understood to include non-citizens and immigrants who are here illegally.

Cornell law professor Stephen Yale-Loehr said court data show “there are over 667,000 cases pending in immigration court, with an average backlog of almost two years. The Trump administration has asked Congress to increase funding to detain more immigrants. Thus, even more immigrants may be detained in the coming months and will have to wait even longer for their day in court.”

ACLU attorney Ahilan Arulanantham, who argued the case in the high court, said the “Trump administration is trying to expand immigration detention to record-breaking levels as part of its crackdown on immigrant communities. … We look forward to going back to the lower courts to show that these statutes, now interpreted by the Supreme Court to require detention without any hearing, violate the Due Process Clause.”