A federal judge upheld Indiana University's requirement for vaccination against the coronavirus in a ruling made public Monday, rejecting arguments from students who contended the mandate was unconstitutional.

The ruling could be influential as colleges and universities across the country are preparing to reopen in the fall and deciding how to protect campuses from the ongoing public health threat of the lethal virus. Hundreds of schools have adopted vaccine requirements. Many others are only encouraging students to get vaccinated.

The split on mandates often follows a red-blue political divide. Colleges that require vaccination are more likely to be located in states that President Joe Biden carried in last year's election.

IU, with about 90,000 students on several campuses, is one of the most prominent public universities in a Republican-led state to adopt a vaccine mandate. Purdue University, also in Indiana, does not have a mandate.

Eight IU students challenged the university's policy in a lawsuit filed last month in the U.S. District Court for the Northern District of Indiana, saying the mandate infringed on their bodily autonomy and medical privacy. Several of the plaintiffs had obtained exemptions that the university offered from the mandate on religious grounds, but they nonetheless viewed the policy as an attack on their rights and sought a preliminary injunction to halt the mandate.

U.S. District Judge Damon Leichty sided with the university in declining to issue an injunction after hearing oral arguments on July 13.

"Recognizing the students' significant liberty to refuse unwanted medical treatment, the Fourteenth Amendment permits Indiana University to pursue a reasonable and due process of vaccination in the legitimate interest of public health for its students, faculty, and staff," Leichty wrote in an opinion dated Sunday. "Today, on this preliminary record, the university has done so for its campus communities. The students haven't established a likelihood of success on the merits of their Fourteenth Amendment claim or the many requirements that must precede the extraordinary remedy of a preliminary injunction."

Leichty, a Trump appointee, wrote in the ruling that the lawsuit posed new and urgent questions.

"No case to date has decided the constitutionality of whether a public university, such as Indiana University, may mandate that its students receive a COVID-19 vaccine," Leichty wrote.

He noted that the most widely used coronavirus vaccines are being administered through emergency use authorization, or EUA, and still do not yet have full approval from the Food and Drug Administration. But the pandemic posed a rare public health threat, the judge wrote, citing the covid-19 death toll in America of more than 600,000.

"Not all EUAs are equal," Leichty wrote, "and the one required for COVID-19 vaccines was more robust than usual."

James Bopp Jr., attorney for the plaintiffs, said in a statement that they would appeal.

"Continuing our fight against this unconstitutional mandate is necessary to guarantee that IU students receive the fair due process they're owed by a public university," Bopp said. "An admitted IU student's right to attend IU cannot be conditioned on the student waiving their rights to bodily integrity, bodily autonomy, and consent to medical treatment like IU has done here."

The university applauded the outcome.

"A ruling from the federal court has affirmed Indiana University's COVID-19 vaccination plan designed for the health and well-being of our students, faculty and staff," IU said in a statement. "We appreciate the quick and thorough ruling which allows us to focus on a full and safe return. We look forward to welcoming everyone to our campuses for the fall semester."

IU's mandate, issued in May, applies to students and employees. So far, an IU spokesman said, about 80% of students, faculty and staff have had at least one vaccine shot. Classes resume in August on the main campus in Bloomington and elsewhere.