A jury has begun deliberating in the trial of Officer William Porter, right, one of six Baltimore police officers charged in the death of Freddie Gray. Porter faces manslaughter, assault, misconduct in office and reckless endangerment charges. (Kevin Richardson/The Baltimore Sun via AP)

As Baltimore braced for a verdict in the first trial related to Freddie Gray’s death while in police custody, Baltimore schools officials warned students that they may risk disciplinary action for taking part in certain protest activities, including walking out of class.

“Students need to understand that we support their right to express their emotions, and that we will facilitate opportunities for them to do so appropriately,” Baltimore City Schools chief executive Gregory E. Thornton wrote in a letter addressed to parents, families and community members. “However, we need to make it clear that student walkouts, vandalism, civil disorder, and any form of violence are not acceptable under any circumstances and that students who participate in such behaviors will face consequences.”

Here's what you need to know after a jury failed to reach a verdict in the trial of William G. Porter, one of six police officers charged in the ​Freddie Gray case​. (Ashleigh Joplin/The Washington Post)

[Freddie Gray case: Jury deliberations begin]

Thornton wrote that the school system’s primary concern is keeping students safe, particularly after the unrest that gripped the city following Gray’s death last spring. High school students were among a group that engaged in a violent confrontation with police at Mondawmin Mall last April, setting off days of protesting, violence and looting.

It’s not just Baltimore City officials who are concerned about the possibility of more unrest. Baltimore County schools postponed and in some cases cancelled all field trips and events in Baltimore City through Friday, December 18. School system spokesman Mychael Dickerson said the decision was made “as a precaution and in consultation with our law enforcement partners.”

But as Thornton’s letter made the rounds on social media on Monday afternoon, many questioned whether his threat of consequences was an effort to silence students’ legal speech and an infringement on their First Amendment rights.

There’s a difference, some pointed out, between violent behavior and staging a walkout, a common and nonviolent form of civil disobedience.

Students who break laws outside of school face sanctions just like anyone else, said Susan Goering, executive director of the ACLU of Maryland. “But students cannot be punished in school for actions that take place out of school, absent some nexus to school activities or in school consequences,” Goering said in a statement. “The school system’s letter ignores these rules, and could result in, and seems to be having the effect of, chilling legitimate, peaceful protest activity.”

Goering said that the school system’s letter “assumes that students only want to express their emotions, not rational views about the conduct of police and lack of accountability, and it misses an opportunity to affirmatively engage students who want to be politically engaged on these issues.”

In the past year, Baltimore high school student activists have organized walkouts to protest public education budget cuts and police brutality; according to the Baltimore City Paper, several were arrested in October for occupying City Hall after efforts to meet with the mayor and police chief failed.

In a statement Monday evening, Baltimore City schools officials said they are “committed to ensuring students have an appropriate venue in which to express their views while also ensuring expectations regarding student conduct are met.”

“There is no intent to quell student voice and we have provided our schools with resources aimed at educating students on constructive ways to express their opinions,” the statement said.

Last spring, Baltimore schools were closed the day after riots erupted, and Thornton issued a statement promising that the “small minority” of students who engaged in violent behavior would be held accountable. “I am deeply angered that the inexcusable actions of those few now threaten to color perceptions about the many,” he wrote at the time. “We are working to identify those students, who will experience consequences in full accordance with the law and City Schools’ code of conduct.”

A schools spokesman did not immediately respond to a question about how many students were disciplined for violent behavior during last April’s unrest.

Read the letter:

Family Community Letter