First, this is not a phenomenon that is unique to the US. Protestors in many places, including the UK, are often arrested or otherwise controlled by police. Protestors in the US are often left alone.

But because you asked about the US specifically, the US Constitution protects a right of freedom of assembly, but this has essentially never been interpreted as a license for large groups of people to do whatever they want. Police will often monitor protests and order them to disperse if the crowd becomes particularly agitated or disruptive. If protestors don't disperse (or actively resist police control), police might starting making arrests.

Where exactly this line should be drawn is enormously controversial and contentious, and both police and protestors have been known to behave poorly. What happens can depend on the issue at hand, the demographics of the police and protestors, and the general political climate.

Illegal protest, disobeying a legal order, vandalism, littering, disrupting the peace, blocking traffic, any other of a list of subjective and discretionary bogged up charges.

As long as they have a "reasonable suspicion" of a crime, they can arrest you.

It's always easy to say "well the DA decided not to prosecute in the end". What is the public going to do about it? Go to the police?

Worst case, they can sue them, which would cost quite a bit of money to the individual, the court tend to cut a lot of slack to cops, then there is qualified immunity, then, even if you get damages, it's paid with public funds and there are no real consequences for the officer anyway.

A good interaction with a cop is an interaction you avoided. Protect & Serve is mostly a bad joke at that point.

You can protest in the US.

You cannot block other people's access like standing in a street or highway. This is infringing upon other people's rights to freely move around.

You cannot riot--loot buildings, set fires, damage vehicles.

You cannot make excessive noise in violation of local noise ordinances.

If police feel that public safety is compromised they may term a protest an illegal assembly. I'm not a fan of this, BUT if the protestors are actively trying to hide, or prevent access to people committing crimes as part of the protest, I have no problem with the police arresting such people for abetting the crime.

In short, protesting does not give you the right to violate the law. Many protestors will knowingly and willingly violate laws in order to protest. If you do so, you should not be upset or surprised when you are arrested.

You should be more concerned with what happens to protesters in more autocratic countries. How many of the protesters were killed by the Iranian government recently? How many Chinese citizens have disappeared protesting the insane COVID lockdowns the last couple days?

Each state has thousands of laws. Chances are you are violating one of them right now. A protestor got too aggressive with someone, blocked someone's path, stepped from public property to private property, was intoxicated in public, violated a pedestrian traffic ordinance, or pretty much anything else that you could ever think of.

If the police ever need a reason to arrest someone, our elected officials have gladly given them that opportunity by passing thousands of unnecessary laws.

If you obstruct pedestrians or cars you can be arrested and legally detained, similarly if your protest goes onto private property you can also be arrested.

[removed]

[removed]

Generally speaking it's purely harassment. Arrest people, throw them in jail for a few hours or days, and then release them 20 miles from wherever they were. Maybe beat them up a bit too.

Please read this entire message

Your submission has been removed for the following reason(s):

Information about a specific or narrow issue (personal problems, private experiences, legal questions, medical inquiries, how-to, relationship advice, etc.) are not allowed on ELI5.

If you would like this removal reviewed, please read the detailed rules first. If you believe this submission was removed erroneously, please use this form and we will review your submission.