The criminal justice process typically begins when a police officer places a person under arrest. An "arrest" occurs when a person has been taken into police custody and is no longer free to leave or move about. The use of physical restraint or handcuffs is not necessary. An arrest can be complete when a police officer simply tells a crime suspect that he or she is "under arrest", and the suspect submits without the officer's use of any physical force. The key to an arrest is the exercise of police authority over a person, and that person's voluntary or involuntary submission.

A police officer may usually arrest a person in the following circumstances:

The Police Officer Personally Observes a Crime

If a police officer personally sees someone commit a crime, the officer may arrest that individual. For example:

• While on street patrol, a police officer sees a purse snatching take place. The officer can apprehend and arrest the purse-snatcher, based on the officer's personal observation of a theft/larceny or robbery.

• A police officer pulls over a vehicle that is being driven erratically, and after administering a Breathalyzer test, sees that the driver's alcohol intoxication level is more than twice the state's legal limit for safe operation of a vehicle. The police officer can arrest the driver for DUI/DWI.

The Police Officer Has "Probable Cause" to Arrest

When a police officer has a reasonable belief, based on facts and circumstances, that a person has committed or is about to commit a crime, the officer may arrest that person. This belief, known as "probable cause," may arise from any number of different facts and circumstances. For example:

• A police officer receives a report of an armed robbery that has just occurred at a liquor store, then sees a man who matches the suspect's exact description running down the street near the store. The officer detains and searches the man, finding a gun and a large amount of cash in his pockets. The officer can arrest the man, based on a probable cause belief that he committed a robbery.

An Arrest Warrant Has Been Issued

When a police officer has obtained a valid warrant to arrest a person, the arrest is lawful. An arrest warrant is a legal document issued by a judge or magistrate, usually after a police officer has submitted a sworn statement that sets out the basis for the arrest. When issued, an arrest warrant typically:

• Identifies the crime(s) committed;
• Identifies the individual suspected of committing the crime;
• Specifies the location(s) where the individual may be found; and
• Gives a police officer permission to arrest the person(s) identified in the warrant.

Challenging An Unlawful Arrest

At all stages of the criminal process, including arrest, police officers must protect citizens' constitutional rights, such as the right to remain silent and the right to be free from unreasonable searches. If these rights are violated, a court may deem the arrest unlawful and order the case against the arrestee dismissed, or certain evidence may be thrown out of the case. Click here to learn more about a defendant's rights when dealing with police.

While a criminal suspect may question the lawfulness of an arrest when it is happening, including the basis for the arrest and the actions of the police officers, that battle is best fought in court rather than on the street.

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