Legal Authority and Limitations of a Security Guard
A security guard is a private citizen whose authority comes from the property owner (or client) who hired them, not from the state. That single fact drives most of this domain. Guards generally hold no more police power than any other citizen: no authority to arrest on a whim, no power to search a person at will, and no right to compel answers. Their lawful leverage is the contractual and property-based authority to set conditions on who may remain on private property.
Key concepts to master: the difference between detention (brief, reasonable restraint to investigate) and arrest (taking a person into custody to answer for an offense); citizen's arrest rules, which vary by jurisdiction but generally require an offense committed in the guard's presence or a felony with reasonable grounds; trespass and the guard's power to revoke permission to be on the property; search and seizure limits, where the guard's authority is strongest over company property (lockers, vehicles on site, packages) when policy clearly gives notice, and weakest over a person's body or personal effects; and use of force as a separate, tightly bounded topic.
Common question traps: assuming a guard has police powers; confusing a store's civil right to ban a person with a criminal arrest power; treating a signed policy as consent to a full body search; and forgetting that authority ends at the property line. Another trap is the guard who is also a sworn officer off-duty-authority then depends on the jurisdiction's rules, not on the uniform.
Rule of thumb: before acting, ask three questions-Am I on my client's property or acting under a specific legal power? Has the person's conduct actually met the legal threshold (not just annoyed me)? And is the least intrusive step enough? If the answer to any is unclear, observe, document, and call the police rather than improvise.