Probable cause

[1] One definition of the standard derives from the U.S. Supreme Court decision in the case of Beck v. Ohio (1964), that probable cause exists when “at [the moment of arrest] the facts and circumstances within [the] knowledge [of the police], and of which they had reasonably trustworthy information, [are] sufficient to warrant a prudent [person] in believing that [a suspect] had committed or was committing an offense.”[2] Moreover, the grand jury uses the probable cause standard to determine whether or not to issue a criminal indictment.

The principle behind the probable cause standard is to limit the power of authorities to conduct unlawful search and seizure of person and property, and to promote formal, forensic procedures for gathering lawful evidence for the prosecution of the arrested criminal.

[4] The term of criminal law, the probable cause standard is stipulated in the text of the Fourth Amendment to the U.S. Constitution: The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.Moreover, in U.S. immigration law, the term “reason to believe” is equivalent to the probable cause standard of criminal law,[5] and should not be confused with reasonable suspicion, which is the legal criterion required to perform a Terry stop in the U.S.

As a legal standard, probable cause is stronger than reasonable suspicion, but weaker than the requirement of evidence to secure a criminal conviction.

In the case of Brinegar v. United States (1949), the Supreme Court defined probable cause as “where the facts and [the] circumstances within the officers’ knowledge, and of which they have reasonably trustworthy information, are sufficient, in themselves, to warrant a belief, by a man of reasonable caution, that a crime is being committed.”[7] The use of probable cause in the United States and its integration in the Fourth Amendment has roots in English common law and the old saying that "a man's home is his castle".

[8] In the 1700s, the British use of the writs of assistance and general warrants, which allowed authorities to search wherever and whenever sometimes, without expiration date, in the American colonies were raised in several court cases.

In the case the lawyer for the merchants James Otis argued that writs of assistance violated the fundamentals of English Law and was unconstitutional.

[11]Later, in Samson v. California, the Supreme Court ruled that reasonable suspicion is not even necessary: The California Legislature has concluded that, given the number of inmates the State paroles and its high recidivism rate, a requirement that searches be based on individualized suspicion would undermine the State's ability to effectively supervise parolees and protect the public from criminal acts by reoffenders.

In this particular case, Place was in LaGuardia Airport in New York City, and DEA agents took his luggage, even though he refused to have his bag searched.

However, In Florida v. Jardines[17] the court ruled that a police officer and narcotic-sniffing dog entering the porch of a home constitutes a search which invokes the requirement of probable cause or a valid search warrant The power of probable cause by K-9 units smelling for drugs is not limited to just airports, but even in schools, public parking lots, high crime neighborhood streets, mail, visitors in prisons, traffic stops, etc.

[18] Under the 2001 USA Patriot Act, law enforcement officials did not need probable cause to access communications records, credit cards, bank numbers and stored emails held by third parties.

[19] However, the text of the Patriot Act limits the application of that statute to issues that clearly involve the national security of the United States.

The latter refers only to the suspect being able to and sometimes having a motive to commit the crime and in some cases witness accounts, whereas probable cause generally requires a higher degree of physical evidence and allows for longer periods of detention before trial.