Final answer:
Probable cause is a legal requirement that necessitates reasonable grounds to believe a crime has been or will be committed, beyond simply knowing a suspect's criminal history. It is a constitutional protection against unreasonable searches and seizures. Specific cases like Terry v. Ohio and Illinois v. Gates have shaped the legal understanding and application of probable cause.
Step-by-step explanation:
An officer's knowledge of a suspect's criminal record does not, by itself, establish probable cause. Probable cause is a legal standard that requires law enforcement to have reasonable grounds to make an arrest, issue a search warrant, or take action, believing that a crime has been committed or that evidence of a crime will be found. Simply knowing a suspect's history is not sufficient.
In scenarios such as the one involving a suspected armed robbery, although the police may recognize a need to act, they must meet the probable cause requirement to justify their actions legally. The principle of probable cause helps protect individuals from unreasonable searches and seizures as indicated in the Fourth Amendment. In Terry v. Ohio, a case that has shaped police practices, the Supreme Court held that police may stop and frisk individuals if they have a reasonable suspicion of criminal activity.
This requirement ensures that the legal process respects individual rights while still allowing law enforcement the ability to perform their duties effectively. For instance, the Illinois v. Gates ruling established the "totality of circumstances" test which courts apply when evaluating whether probable cause exists in a situation. All these elements together form the constitutional framework for assessing police actions regarding searches and arrests.