Under what circumstances can a security guard make an arrest?

A security guard is empowered to make an arrest primarily when they observe a crime being committed. This authority is grounded in the legal principles of citizen's arrest, which allow individuals, including security personnel, to detain someone if they witness an unlawful act taking place. The rationale behind this is to allow immediate intervention to prevent further criminal activity and to protect property and individuals present at the scene.

While suspicion of unusual behavior is a factor that a security guard may consider in assessing the situation, it does not provide sufficient legal grounds for an arrest. Similarly, being instructed by a supervisor may guide the action taken, but it doesn't alter the legal authority to make an arrest unless a crime is occurring. Lastly, while trespassing can be a valid reason for a security guard to intervene, the act of making an arrest becomes justifiable only if it's directly connected to the commission of a crime. Therefore, the most definitive circumstance that allows for an arrest is the direct observation of a crime in progress.