When does a peace officer have the authority to make an arrest without a warrant?

A peace officer has the authority to make an arrest without a warrant when they observe a crime being committed in their presence. This principle is rooted in the notion of immediate action; if an officer witnesses a crime firsthand, they are positioned to act decisively to prevent further harm, preserve public safety, and ensure that the suspect can be apprehended. This direct observation provides the officer with probable cause, which is a key requirement for warrantless arrests.

In contrast, having prior knowledge of a suspect's criminal history does not constitute grounds for arrest without a warrant; it is the observation of the crime itself that grants the officer the authority. An anonymous tip, while it may raise suspicion, typically does not provide the necessary probable cause to justify an immediate arrest. Similarly, reasonable suspicion is a lower standard than probable cause and is primarily used for temporary detentions and investigations rather than actual arrests. Thus, the ability to act on witnessing a crime directly is crucial to the enforcement of law and order by peace officers.