A security guard arrests a person believing a felony robbery occurred. Investigation reveals the suspect's roommate had given permission to take the property — no felony was in fact committed. Under §837(3), what is the guard's exposure?

Explanation

Penal Code §837(3) requires both (1) that 'a felony has been in fact committed' AND (2) that the arrestor have reasonable cause to believe the arrestee committed it. If no felony was in fact committed — even with reasonable belief — the arrest fails to meet §837(3) and exposes the private person to false-arrest civil liability (Cervantez v. J.C. Penney Co. (1979) 24 Cal.3d 579). This is the key difference from peace-officer §836 authority, which generally protects officers acting on reasonable cause even if no crime occurred. Where §837(1) (in-presence) applies, it provides a surer authority.