What does an officer need to establish a lawful arrest?

To establish a lawful arrest, an officer must demonstrate probable cause, which is the reasonable belief that a person has committed a crime or is about to commit one. This standard is essential because it protects individuals from arbitrary arrest and detention. Probable cause is based on the totality of the circumstances known to the officer at the time, which can include evidence, observations, and reports that collectively create a reasonable basis for the arrest.

In contrast, the other options do not provide a sufficient legal basis for an arrest. For example, while having a witness present or a signed complaint might support an officer's case or investigation, they are not required components to establish the legality of an arrest. Similarly, written consent from a suspect might be relevant in certain scenarios, particularly in the context of searches, but it is not necessary to justify an arrest. Thus, establishing probable cause remains the fundamental requirement for making a lawful arrest.