According to the Fourth Amendment of the U.S. Constitution, the police can only arrest a person when they have probable cause, which means that they have to have a good reason to believe there's been a crime and that the suspect committed it.

When the police arrest a criminal suspect, the case passes to a prosecutor, who examines the evidence and decides whether or not to file charges. In felony cases, which are crimes carrying penalties of a year or more in prison, the prosecutor may enlist the help of a grand jury.

When a suspect has been charged with a crime, a trial date is set by a judge at a hearing or arraignment. At this time, the judge will also decide whether or not the defendant is to be returned to custody or be released on bail until the trial.

The U.S. Constitution protects you from unjust detention or unfair treatment by the authorities in a number of ways. According to the Fourth Amendment, the police are not allowed to arrest you unless they have probable cause.

Bail is an amount of money, or the equivalent, that you give to the court as a guarantee that you'll appear for trial as ordered. You can post bail in the form of cash, a check, property, or a bond.

If you've been charged with a misdemeanor, you'll generally be released from custody immediately and ordered to appear in court at a certain time. If you've been charged with a more serious crime, you'll appear before a judge at an initial hearing or arraignment, at which time bail will be set.

According to U.S. Code, if you resist arrest by any person designated to make arrests, you can be fined and imprisoned for up to a year. State laws vary, but generally anybody who willfully resists, delays, or obstructs a peace officer in the performance of his or her duty is in violation of the Penal Code.

Technically, you're under arrest when you're no longer free to walk away from the arresting officer, who is obliged to inform you that you're under arrest.