Armored vehicles mounted with machine guns may be rolling through the streets, but Ferguson, Mo., is still part of the United States, and the Constitution still applies.

Protests have continued for several days since an officer shot and killed 18-year-old Michael Brown in Ferguson on Saturday. Dozens of people have been arrested, including Washington Post reporter Wesley Lowery. And reports from Ferguson suggest that some local authorities might be falling short of their obligations to respect the rights of citizens and to comply with judicial interpretation of the First and Fourth Amendments. Below are a few areas in which local authorities could be violating people's rights.

1. The mayor asked protesters to be respectful and to go home at night.

Ferguson's mayor and the city council issued a letter Wednesday asking protesters to restrain their activities. "We ask that any groups wishing to assemble in prayer or in protest do so only during daylight hours in an organized and respectful manner," the letter read. Thomas Jackson, the police chief, explained to the New York Times that the request was not a curfew, but last night police seemed intent on enforcing it as such anyway.

It is unclear whether the city government had the authority to issue its letter, given that the First Amendment protects "the right of the people peaceably to assemble."

This same issue arose during the World Trade Organization's meeting in Seattle in 1999, when the city prohibited anyone from entering a 25-block area downtown, except for those participating in the meeting. Protesters were enraged and sued the city. The Ninth Circuit Court ruled that Order No. 3, as the city of Seattle's ban was known, was constitutional. The court held that the city had broad authority to prevent violence and maintain public order, though the ruling noted with a few caveats. For one, the court said that city police had overstepped their bounds in apparently focusing on protesters who were opposed to the WTO and ignoring those who supported it.

In Ferguson, while there was certainly some looting and vandalism over the weekend, it is not clear there is still any danger to public safety or whether the peaceful protests are obstructing officers who are trying to apprehend vandals, as the Ninth Circuit determined had occurred in Seattle.

In any case, there does not appear to be any justification for asking protesters to be "organized and respectful," said Lee Rowland, an attorney at the American Civil Liberties Union. "I think there are many people in Ferguson who are feeling that the police are not especially deserving of respect right now, and the First Amendment does not mandate that," she said.

2. Police have asked citizens not to record their activities.

Lowery wrote that before he was taken away, an officer told him to stop recording video. Other protesters have also said that they've been told to put away their phones. As The Post's Andrea Peterson has explained, the courts have consistently recognized that citizens have a right to document police activity. Police also need a warrant to confiscate or search citizens' cameras or phones.

3. Police are deploying tear gas and rubber bullets against protesters.

The police have to use force from time to time to apprehend criminals and keep the public safe. That's why they're there. That doesn't mean all forms of police violence are always justified.

The Supreme Court defined the judicial standard for police violence in the 1989 case of a diabetic man who, desperate for sugar, had gone into a convenience store for a bottle of orange juice. He saw the store was crowded and decided to go elsewhere, but a police officer saw him leave hurriedly, became suspicious and stopped the man's car. By this point, the man was apparently delirious. He got out of the car and ran around in circles before passing out on the ground. The officer called for reinforcements, who treated the man roughly while denying his requests for sugar. "I've seen a lot of people with sugar diabetes that never acted like this," said one officer, according to the court. "Ain't nothing wrong with the m-----f----- but drunk. Lock the son of a b---- up."

The court ruled that the police officers' use of force in the case was "objectively unreasonable" and unconstitutional. In the 25 years since, lower courts have interpreted this admittedly imprecise standard of reasonableness in various ways.

The situation in Ferguson in the past few days has at times been chaotic and violent, but, by all accounts, the demonstrations have generally been peaceful. It is difficult to say whether a court would agree that it is reasonable to shoot tear gas canisters or rubber bullets at protesters who pose no obvious threat to public safety.

4. Area law enforcement consistently arrest and search black people more frequently than whites.

In a report last year, Missouri's attorney general concluded that Ferguson police were twice as likely to arrest blacks as whites during traffic stops. Jeffrey Mittman, director of the ACLU's Missouri chapter, said the pattern is indisputable.

"The numbers are consistently shocking, disheartening, and show a racial disparity," he said. "If you are African American, you are more likely to be stopped, you are more likely to be searched, you are more likely to be arrested, and you are actually less likely to have contraband on you than if you are white."

The state conference of the NAACP has also filed a complaint against St. Louis County police on the same grounds. The county police department has been tasked with investigating Brown's death, and one of Missouri's congressmen, Rep. Lacey Clay, has written a letter suggesting county police cannot be trusted to do so impartially. A pattern of discrimination on the part of law enforcement would be a violation of federal law, Clay wrote.