Under what circumstance can police officers arrest someone without a warrant?

Police officers can arrest someone without a warrant when a crime is committed in their presence. This is known as a "breach of the peace" exception to the warrant requirement. The principle behind this is that if an officer witnesses a crime occurring, they have the authority to intervene instantly to maintain order and public safety. This allows law enforcement to act swiftly in preventing further criminal activity, protecting potential victims, and preserving evidence.

Warrantless arrests based on an officer's direct observation of a crime help ensure that law enforcement can fulfill their primary responsibilities efficiently and effectively. This principle is rooted in both statutory law and case law, which support the necessity of immediate action when a law enforcement officer has firsthand knowledge of a crime taking place.