1. Define probable cause, and describe the type of facts that the police may rely on in determining probable cause.
    
2. Explain the difference between the Aguilar-Spinelli test for evaluating whether the police may rely on an informant, and the totality-of-the-circumstances test.
    
3. Describe the process for obtaining an arrest warrant.
    
4. Explain when an arrest warrant is required for felony arrests, and for misdemeanor arrests in public and in the home.
    
5. Define exigent circumstances.
    
6. Describe the circumstances under which the police rely on using deadly force, and when they need to use non-deadly force.
    
7. Explain the law as it pertains to misdemeanors, citations, and arrests.

SUMMARY: An arrest satisfies the reasonableness requirement of the Fourth Amendment when the seizure is supported by probable cause and the arrest is executed or carried out in a reasonable fashion.

The first requirement is probable cause. Police officers have probable cause where “the facts and circumstances within their knowledge and of which they had reasonably trustworthy information are sufficient in themselves to warrant a man of reasonable caution in the belief that an offense has been or is being committed.” The Supreme Court, in an effort to clarify this standard, has explained that probable cause is more than reasonable suspicion and less than the beyond-a-reasonable-doubt standard required for a criminal conviction. This test balances the responsibility of law enforcement to investigate crimes and to apprehend offenders with the protection of individual privacy.

Probable cause to arrest an individual may be developed through an officer’s five senses: sight, sound, smell, touch, and taste. Probable cause also may be based on hearsay, or “secondhand” information from victims, eyewitnesses, police officers, and informants. Courts are particularly cautious in accepting the accuracy of tips from informants. The Supreme Court initially relied on the Aguilar-Spinelli two-prong test for informants. The affidavit under this test must establish both the informant’s veracity and the informant’s basis of knowledge. These requirements proved difficult to satisfy, and in 1983, in Illinois v. Gates, the Supreme Court adopted a totality-of-the-circumstances test. The veracity and basis-of-knowledge prongs under Gates are described as relevant considerations in determining whether there is probable cause rather than as separate considerations.

The second requirement is that the arrest must be carried out in a reasonable fashion. The Fourth Amendment provides that “no Warrant shall issue but upon probable cause, supported by Oath or affirmation.” The central element that is important in the warrant process is that probable cause must be established in a non-adversarial hearing before a neutral and objective magistrate capable of determining probable cause. The warrant must with “particularity” specify the person to be arrested, the time and place of the offense, and the specific statutory violation. This must be supported by an affidavit swearing to the facts on which the probable cause is based. In Gerstein v. Pugh, the U.S. Supreme Court held that a police officer’s on-the-scene assessment of probable cause provides legal justification for the arrest of an individual. Once the suspect is taken into custody, the Fourth Amendment requires that a Gerstein hearing determine whether a “reasonable person would believe that the suspect committed the offense.”

The Supreme Court has expressed a preference for warrants. In United States v. Watson, the U.S. Supreme Court nevertheless upheld the warrantless arrest of individuals in public based on probable cause that they had committed a felony. This was permissible even when the officers could have obtained a warrant. The law as to misdemeanors is somewhat different. In Atwater v. City of Lago Vista, the U.S. Supreme Court held that the common law and the historic practice of the federal government and the fifty states establish that it is constitutionally permissible under the Fourth Amendment to arrest an individual without a warrant for a misdemeanor when the offense is committed in an officer’s presence.

Watson left open the question whether a warrant is required to arrest an individual in his or her home. In Payton v. New York, the U.S. Supreme Court held that an arrest warrant founded on probable cause is required to arrest an individual in his or her home when there is “reason to believe that a suspect is within.” The Court reasoned that the unreasonable physical entry into the home is the “chief evil at which the Fourth Amendment is directed.” There is an exigent-circumstances exception to the warrant requirement in those instances in which the police have probable cause that they are in hot pursuit of a suspect, that there is a threat to public safety, or that there is probable cause that evidence may be destroyed or that a suspect may flee. The Supreme Court recently recognized the exigent circumstance of “emergency aid” as an additional exception to the Fourth Amendment warrant requirement.

In 1985, in Tennessee v. Garner, the Supreme Court held that the police may resort to deadly force to apprehend a fleeing felon under the Fourth Amendment where the officer has probable cause to believe that the suspect threatens the officer with a weapon or where there is probable cause to believe that he or she has committed a crime involving the infliction or threatened infliction of serious physical harm. The officer, where feasible, should issue a warning. Four years later, in Graham v. Connor, the U.S. Supreme Court held that the exercise of non-deadly force also is to be analyzed under the Fourth Amendment reasonableness standard. In evaluating the officer’s response, courts must evaluate the circumstances confronting the police at the time rather than consider the situation with “20/20 hindsight.” The relevant facts and circumstances include the severity of the crime, whether the suspect posed an immediate threat to the officers, and whether the suspect was actively resisting or evading arrest.