Arrest or custodial arrest is the process in which the police take physical possession or custody of a person whom they have probable cause to believe committed a criminal offense. Arrest is distinguishable from other circumstances in which the police stop, detain, or otherwise interact with persons because it is generally the point at which a person is not free to leave or walk away from the police. Arrest is also the point at which some Constitutional rights and protections are provided to the accused. A person who is placed in handcuffs or otherwise physically restrained is clearly under arrest—but in some circumstances a person may be under arrest due to threats or intimidation from the police.

In Maryland, an arrest or custodial arrest occurs when law enforcement takes physical custody of an individual based on probable cause that the person has committed a criminal offense. This is a more severe action than a mere stop or detention, as it typically means the individual is not free to leave the presence of the police. During an arrest, the individual's Constitutional rights, such as the right to remain silent and the right to an attorney, become particularly relevant. The use of handcuffs or other physical restraints usually signifies an arrest, but an arrest can also occur if the police use threats or intimidation to such a degree that a reasonable person would not feel free to leave. Maryland law requires that police officers adhere to the standards set forth by the U.S. Constitution and state statutes when making an arrest, ensuring that the individual's rights are protected from the moment of arrest.