Early on April 29, dozens of protesters who were arrested in connection with the Baltimore demonstrations were freed when the paperwork wasn't completed in time. The public defender filed a habeas corpus petition that demanded that people who weren't charged within 24 hours be released.
Police department officials were unable to pull together the paperwork because of a logjam. The police commissioner noted that they released the protesters but that he did have future prosecution in mind. He noted that they aren't giving up on the charges.
These protests came on the heels of the death of 25-year-old African American Freddy Gray. Gray died while he was in police custody, which incited a variety of demonstrations.
For these protesters, knowing their rights and understanding how to protect those rights might help them if officials do file charges later in time. While they were released from jail, that doesn't mean that they won't have to deal with the criminal justice system later.
One important thing for anyone who is considering a protest should know is that the First Amendment provides protections for peaceable protests. That means that violent demonstrations like the rioting that took place in Baltimore Monday night wouldn't be protected by the amendment.
Those who have been arrested for something they feel violates their Constitutional rights should seek to find out if the circumstances surrounding their arrest are covered under the protections offered. Once that determination is made, you should look into the possible defense options you have so that you can make an informed decision about how to handle your case.
Source: NBC News, "101 Baltimore Protesters Go Free as Arrest Paperwork Backs Up," M. Alex Johnson and Jon Schuppe, April. 29, 2015