Multiple Harvard University professors have been arrested after blocking traffic to protest President Trump’s gradual rollback of the Obama-era Deferred Action for Childhood Arrivals (DACA) amnesty program, which legal experts said was on constitutionally shaky ground.

Harvard professor Kirsten Weld organized the protest, which included professors from fives Boston-area colleges, on Facebook and Twitter. The professors distributed a media advisory ahead of the protest, stating their intention to form a human chain and “sit down in the street and remain seated until they are removed by Cambridge police.”

At least 20 professors were arrested Thursday evening after blocking traffic, the Harvard Crimson reported.

The protest took place despite the fact that Trump has openly stated that he wants to preserve DACA’s protections for the 800,000 illegal immigrants who previously arrived in the country as children.

The purpose of the protest, according to the Facebook description, was to “demand that Congress act promptly and without compromise to safeguard our students.”

The DACA rollback is delayed for six months, and Trump has already said that DACA recipients “have nothing to worry about.” The protest took place anyway.

“It’s not business as usual because the Trump administration is targeting our students,” Weld told the Crimson. (RELATED: Harvard Prof: School President Abetting Decline From ‘Truth’ To ‘Change’)