The Fourth Amendment further provides that a search and seizure must be authorized with a warrant that is supported by probable cause. However, the Fourth Amendment does not specifically define the term probable cause.
What is probable cause? Generally speaking, probable cause is described from the point of view of a reasonable person. In other words, probable cause is an objective test and therefore, it can’t simply stem from a police officer’s hunch or suspicion that a crime has been committed. Specific facts and circumstances are required to make an adequate showing of probable cause that a crime has been committed or that evidence of a crime exists at the location that is to be searched.
When is probable cause not required for a search and seizure? Although probable cause is generally required to support a valid search and seizure, there are certain exceptions to this rule. First, police typically will ask a person for consent to search. If a person consents to a search, probable cause is unnecessary. Additionally, if police arrest a person, they are authorized to conduct a search pursuant to the arrest. There is also an exception to the requirement of probable cause in certain emergency situations. If there is a threat to public safety or a risk that evidence will be lost or destroyed, police are not required to make a showing of probable cause in order to conduct a search and seizure. Finally, if police are lawfully present at a location and contraband is in “plain sight,” probable cause is unnecessary for the police to seize the evidence.
What happens if police illegally seize evidence? Only evidence that is obtained according to the protections afforded by the Fourth Amendment may be used in a court of law. Any evidence that is obtained in violation of a person’s constitutional rights is subject to the “exclusionary rule.” In other words, illegally obtained evidence is excluded from court and cannot be used as evidence against a person who has been charged with committing a crime.