Harvard University won a reprieve in its fight to enrol international students, after the Trump administration appeared to walk back its initial decertification and a federal judge upheld a block on the government’s order.

The Department of Homeland Security said Thursday it would now give Harvard University 30 days to prove it meets the requirements of the Student and Exchange Visitor Programme (SEVP), which authorises universities to host academics on visas.

A letter from DHS Secretary Kristi Noem noted the agency’s “intent to withdraw” certification Harvard needs to have foreign students on campus.

“Failure to respond to this notice within the time allotted will result in the withdrawal of your school’s certification,” she wrote.

A previous notice from 22 May revoked Harvard’s certification with SEVP, prompting a swift lawsuit from the university and an equally rapid restraining order from a judge.

US District Judge Allison Burroughs indicated Thursday she would later issue a longer-term hold, known as a preliminary injunction, that would stand while the case played out in court. That development would allow international students and faculty to continue studying at Harvard during ongoing litigation.

The legal battle is being closely watched by other US universities and the thousands of foreigners who study at Harvard and around the country.

There are two main questions at play in Harvard’s lawsuit, lawyers say.

Do the government’s reasons for targeting Harvard’s participation in the student visa programme hold up under the law?

And, are those reasons legitimate, or just a pretext for punishing Harvard for constitutionally protected speech the administration dislikes?

While legal experts agree the Trump administration could lose if courts find it targeted Harvard for ideological reasons, the government has taken steps that could help it prevail – with broader, thorny implications.

Looming over the showdown is a bigger question: Can the US government dictate what universities can teach, who they can hire, and who can enrol?

“This could be the type of case that could, on a fast track-basis, flow from the district court to the First Circuit to the US Supreme Court,” said Aram Gavoor, an associate dean at George Washington University Law School and a former Department of Justice attorney.

America’s academic visas on which international students, researchers and faculty rely to study in the US is overseen by the Immigration and Customs Enforcement (ICE) agency, a subsidiary of the Department of Homeland Security.

To participate, universities must receive certification from DHS through the Student and Exchange Visitor Programme (SEVP). The government last week revoked Harvard’s SEVP certification, gutting its ability to host international students and researchers.

“In terms of the general authority of DHS, it’s quite strong. It’s a certifying agency for this programme and there’s a variety of bases on which decertification can take place,” Mr Gavoor said. Courts tend to be deferential to the agency, as well.

“There are certain limits to it, though,” he said.

The US Constitution’s First Amendment, which guarantees free speech for individuals as well as corporations and entities like Harvard, is a powerful protection – and one that Harvard invoked again and again in its lawsuit.

If judges determine DHS’ basis for withdrawing Harvard’s certification stems from ideological differences and violates the university’s free speech rights, the court could rule against the government.

“A lot will turn on whether the courts conclude whether the First Amendment is implicated here,” Mr Gavoor said.

References to Harvard’s alleged ideological leanings appear throughout the Trump administration’s letters and statements – possibly problematic for the White House in court, legal experts say.

An 11 April letter ordered the university to make significant changes to its operations, including bringing in a third party “to audit the student body, faculty, staff, and leadership for viewpoint diversity.”

President Trump attacked Harvard on Truth Social for “hiring almost all woke, Radical Left, idiots and ‘birdbrains'”. A separate post called for the university to lose its tax-exempt status “if it keeps pushing political, ideological, and terrorist inspired/supporting ‘Sickness'”.

In her initial 22 May letter to Harvard about student visa eligibility, Homeland Security Secretary Kristi Noem said Harvard was “hostile to Jewish students, promotes pro-Hamas sympathies, and employs racist ‘diversity, equity, and inclusion’ policies.”

Harvard argues that the Trump administration’s actions are not about combatting antisemitism or keeping Americans safe.

Revoking visa certification is “the latest act by the government in clear retaliation for Harvard exercising its First Amendment rights to reject the government’s demands to control Harvard’s governance, curriculum, and the ‘ideology’ of its faculty and students,” the school says in its lawsuit. It also alleges the government violated Harvard’s right to due process and ignored proper procedures for taking action against it.

“The administration is making clear that they are going after Harvard on account of viewpoints it’s ascribing to Harvard students and faculty and the institution itself,” said Will Creeley, Foundation for Individual Rights and Expression legal director.

“The smoking gun is very smoky indeed, it’s right out there,” he said.

Harvard must comply with federal non-discrimination laws that bar prejudice based on race, gender, national origin, or other protected classes, but “that doesn’t mean that the federal government can dictate acceptable pedagogy in Harvard’s classrooms,” he said.

Decades of legal precedent and a critical 1957 US Supreme Court decision underpin this concept, said Mr Creeley.

Despite Harvard’s argument, nuances could complicate its case.

The US historically screens prospective international students for viewpoints it deems unsafe, which could include allegedly supporting terror or totalitarian regimes. In the past, communist leanings were used to bar foreign academics from the US. Title VI of the Civil Rights Act prohibits discrimination against Jewish students.

Secretary Noem’s letter to Harvard in on 22 May invokes these concepts to justify pulling certification, meaning it could “read in a way where all that conduct is potentially unlawful” on the university’s part, Mr Gavoor said.

“The government could win here,” he said.

Even if a judge bans the visa policy, Trump may already have won by chilling international enrollment, said Simon Sandoval-Moshenberg, an immigration attorney representing Kilmar Abrego Garcia in a high-profile deportation case.

“It’s similar to self-deportation. They want people to self-unenrol,” he said.

At the White House on Wednesday, President Trump floated the idea of capping international students at 15% of Harvard’s student body.

“We have people [who] want to go to Harvard and other schools,” he said. “They can’t get in because we have foreign students there.”