The Fourth Amendment to the United States Constitution is part of the Bill of Rights. It prohibits unreasonable searches and seizures. In addition, it sets requirements for issuing warrants: warrants must be issued by a judge or magistrate, justified by probable cause, supported by oath or affirmation, and must particularly describe the place to be searched and the persons or things to be seized.
In United States criminal law, probable cause is the standard by which police authorities have reason to obtain a warrant for the arrest of a suspected criminal or the issuing of a search warrant. It is also the standard by which grand juries issue criminal indictments. The principle behind the standard is to limit the power of authorities to perform random or abusive searches, and to promote lawful evidence gathering and procedural form during criminal arrest and prosecution. The standard also applies to personal or property searches.
A citizen's arrest is an arrest made by a private citizen – that is, a person who is not acting as a sworn law-enforcement official. In common law jurisdictions, the practice dates back to medieval England and the English common law, in which sheriffs encouraged ordinary citizens to help apprehend law breakers.
Hiibel v. Sixth Judicial District Court of Nevada, 542 U.S. 177 (2004), is a United States Supreme Court case in which the Court held that a statute requiring suspects to disclose their names during a valid Terry stop does not violate the Fourth Amendment if the statute first requires reasonable suspicion of criminal involvement, and does not violate the Fifth Amendment if there is no allegation that their names could have caused an incrimination.
Terry v. Ohio, 392 U.S. 1 (1968), was a landmark decision of the Supreme Court of the United States in which the Court ruled that it is not unconstitutional for American police to "stop and frisk" a person they reasonably suspect to be armed and involved in a crime. Specifically, the decision held that it is not a violation of the Fourth Amendment to the U.S. Constitution's prohibition on unreasonable searches and seizures when a police officer stops a suspect on the street and questions him or her even without probable cause to arrest, so long as the police officer has a reasonable suspicion that the person has committed, is committing, or is about to commit a crime. The Court also ruled that the police officer may perform a quick surface search of the person's outer clothing for weapons if they have reasonable suspicion that the person stopped is "armed and presently dangerous". This reasonable suspicion must be based on "specific and articulable facts", and not merely upon an officer's hunch.
A Terry stop in the United States allows the police to briefly detain a person based on reasonable suspicion of involvement in criminal activity. Reasonable suspicion is a lower standard than probable cause which is needed for arrest. When police stop and search a pedestrian, this is commonly known as a stop and frisk. When police stop an automobile, this is known as a traffic stop. If the police stop a motor vehicle on minor infringements in order to investigate other suspected criminal activity, this is known as a pretextual stop. Additional rules apply to stops that occur on a bus.
A traffic stop, commonly referred to as being pulled over, is a temporary detention of a driver of a vehicle by police to investigate a possible crime or minor violation of law.
Reasonable suspicion is a legal standard of proof in United States law that is less than probable cause, the legal standard for arrests and warrants, but more than an "inchoate and unparticularized suspicion or 'hunch'"; it must be based on "specific and articulable facts", "taken together with rational inferences from those facts", and the suspicion must be associated with the specific individual. If police additionally have reasonable suspicion that a person so detained is armed and dangerous, they may "frisk" the person for weapons, but not for contraband like drugs. However, if the police develop probable cause during a weapons frisk, they may then conduct a full search. Reasonable suspicion is evaluated using the "reasonable person" or "reasonable officer" standard, in which said person in the same circumstances could reasonably suspect a person has been, is, or is about to be engaged in criminal activity; it depends upon the totality of circumstances, and can result from a combination of particular facts, even if each is individually innocuous.
Atwater v. Lago Vista, 532 U.S. 318 (2001), was a United States Supreme Court decision which held that a person's Fourth Amendment rights are not violated when the subject is arrested for driving without a seatbelt. The court ruled that such an arrest for a misdemeanor that is punishable only by a fine does not constitute an unreasonable seizure under the Fourth Amendment.
Edward C. Lawson was an African American civil rights activist, who was the plaintiff in the case of Kolender v. Lawson, 461 U.S. 352 (1983), in which the United States Supreme Court ruled that a California statute authorizing a police officer to arrest a person for refusing to present identification was unconstitutionally vague.
"Stop and identify" statutes are laws in several U.S. states that authorize police to lawfully order people whom they reasonably suspect of a crime to state their name. If there is not reasonable suspicion that a crime has been committed, is being committed, or is about to be committed, an individual is not required to provide identification, even in these states.
Kolender v. Lawson, 461 U.S. 352 (1983), is a United States Supreme Court case concerning the constitutionality of vague laws that allow police to demand that "loiterers" and "wanderers" provide “credible and reliable” identification.
Illinois v. Lidster, 540 U.S. 419 (2004), was a case in which the Supreme Court of the United States ruled that the Fourth Amendment permits the police to use a roadblock to investigate a traffic incident.
United States v. Brignoni-Ponce, 422 U.S. 873 (1975), was the case in which the Supreme Court determined it was a violation of the Fourth Amendment for a roving patrol car to stop a vehicle solely on the basis of the driver appearing to be of Mexican descent. A roving patrol car must have articulable facts that allow for an officer to have a reasonable suspicion that the person is carrying illegal aliens beyond their ethnicity. The Court handed down a 9-0 decision that affirmed the Circuit Court's ruling in the case.
Whren v. United States, 517 U.S. 806 (1996), was a unanimous United States Supreme Court decision that "declared that any traffic offense committed by a driver was a legitimate legal basis for a stop."
R v Kang-Brown, [2008] 1 S.C.R. 456, 2008 SCC 18, is a constitutional decision by the Supreme Court of Canada on the limits of police powers for search and seizure. The Court found that police do not have the right to perform a sniffer-dog search of public spaces when such search is not specifically authorized by statute. In this case, a suspect's section 8 rights under the Canadian Charter of Rights and Freedoms ("Charter") were violated when a police officer stopped him at a bus station and sniffer-dog searched his bag finding drugs in his possession.
United States v. Mendenhall, 446 U.S. 544 (1980), was a United States Supreme Court case that determined "seizure" occurs when an officer uses displays of authority to detain a person.
Refusing to assist a police officer, peace officer or other law enforcement officer is an offence in various jurisdictions around the world. Some jurisdictions use the terminology '"refusing to aid a police officer" or "failure to aid a police officer".
Rodriguez v. United States, 575 U.S. ___ (2015), was a United States Supreme Court case which analyzed whether police officers may extend the length of a traffic stop to conduct a search with a trained detection dog. In a 6–3 opinion, the Court held that officers may not extend the length of a traffic stop to conduct a dog sniff unrelated to the original purpose of the stop. However, the Court remanded the case to the United States Court of Appeals for the Eighth Circuit to determine whether the officer's extension of the traffic stop was independently justified by reasonable suspicion. Some analysts have suggested that the Court's decision to limit police authority was influenced by ongoing protests in Ferguson, Missouri.
United States v. Drayton, 536 U.S. 194 (2002), was a case in which the United States Supreme Court clarified the applicability of Fourth Amendment protections to searches and seizures that occur on buses, as well as the function of consent during searches by law enforcement. During a scheduled stop in Tallahassee, Florida, police officers boarded a Greyhound bus as part of a drug interdiction effort and interviewed passengers. After talking to two of the passengers and asking if they could "check [their] person", officers discovered the two passengers had taped several packages of cocaine to their legs. At trial, the passengers argued that officers violated their Fourth Amendment rights against unreasonable searches and seizures because the police engaged in coercive behavior and never informed them that their participation in the drug interdiction efforts was voluntary.
