Final answer:
Reasonable police officers require probable cause to arrest, search, or seize based on facts and inference that a crime has been committed, that evidence is in a specific place, or items are illegal or forfeitable, all under the protection of the Fourth Amendment.
Step-by-step explanation:
The facts and circumstances which would cause a reasonable police officer to believe that a crime has been committed and a particular person committed it include direct evidence of a crime, such as a witness testimony or surveillance footage. Additionally, for a police officer to search a place, they must have probable cause to believe that evidence of a crime is in the location. Finally, to seize items, officers need probable cause to consider the items as contraband, evidence of a crime, or legally forfeitable.
Probable cause is a legal standard that is lower than the one required for conviction. It only requires a reasonable belief, which must be more than a mere suspicion. As established in Terry v. Ohio, police may stop and frisk a person if there is reasonable suspicion for both the stop and the potential armed status of the individual. Nonetheless, the Fourth Amendment provides protection against unreasonable searches and seizures, mandating that a warrant is generally required unless certain exceptions apply, such as exigent circumstances, consent, or if the items are in plain view.