COLUMBUS, Ohio (WCMH) — Ohio Attorney General Dave Yost has warned universities that students arrested during pro-Palestine protests may face felony charges under a 70-year-old law meant to target the Ku Klux Klan.

In a letter sent Monday to the state’s public universities, Yost said a 1953 “anti-disguise” law could apply to mask-wearing students protesting against Israel’s war in Gaza. The law makes it a fourth-degree felony for two or more people to commit any crime together “while wearing white caps, masks, or other disguise.”

At least 40 people were arrested during peaceful protests on Ohio State University’s campus in late April, including 18 students. All protesters were charged with criminal trespassing, a low-level misdemeanor. But under his interpretation of the state’s anti-disguise law, Yost said protesters could face up to a year and a half in prison and $5,000 in fines.

“I do not wish to see anyone’s First Amendment rights abridged, nor see anyone surprised that they violated the law,” Yost wrote. “The First Amendment is a shield against the government, not a sword against fellow students.”

Dozens — if not hundreds — of protesters wore face coverings during pro-Palestine protests at Ohio State and other universities, whether they were the black-and-white checkered keffiyehs known as a symbol of Palestinian resistance or blue KN95 face masks. At an antiwar protest at Ohio State on May 1, protesters handed out free KN95s alongside pita sandwiches and slices of watermelon.

Some protesters use face coverings to shield their identities from law enforcement or would-be harassers who post their images and identities online. Others mask to prevent the spread of COVID-19 — particularly immunocompromised or otherwise disabled people. COVID-19 infections hospitalized 61 people and killed 12 in Ohio in the last week of April, according to the Ohio Department of Health.

“In the first place, students should protest within the bounds of the law, and not commit crimes,” Yost wrote. “In the second place, they should own their advocacy and avoid wearing masks.”

According to the Southern Poverty Law Center and the Free Speech Center at Middle Tennessee State University, states began passing anti-mask laws in the mid-20th century to combat the violence perpetrated by masked members of the Ku Klux Klan — hence the reference in Ohio’s law to “white caps.” At least a dozen states have anti-mask laws similar to Ohio’s. Such laws have been challenged at state and federal levels for violating First Amendment rights, to mixed results.

Last May, a neo-Nazi group praising Hitler and fitted with swastikas protested outside a drag brunch fundraiser at Land Grant Brewing Company. Most of the neo-Nazis wore black ski masks and red sunglasses to cover their faces.

Ohio State University Police and the Ohio State Highway Patrol arrested 36 people on Ohio State’s campus during a pro-Palestine protest on April 25. Students, calling on Ohio State to disclose and divest its financial ties to companies affiliated with Israel’s war in Gaza, had set up tents with plans to have an encampment similar to those seen at universities across the U.S.

But after five hours of peaceful protests, chants and prayer, law enforcement in riot gear forcibly dispersed the crowd of several hundred, pushing protesters to the ground to handcuff them and dragging others toward county sheriff’s buses. Ohio State had previously warned that setting up an overnight encampment would violate the university’s space rules.

Days later, Ohio State President Ted Carter said in an email to the university community that the decision to arrest protesters was “not about limiting free speech,” but to avoid “significant safety issues.”

A spokesperson for Ohio State said the university is “reviewing” Yost’s letter but did not say how it might impact previously-charged protesters.