This guide covers the private security and investigations industry from formation and licensure through incident response, litigation, and the contract terms that allocate the risk. It begins with the licensing architecture — company license, individual registration, armed endorsement, training hours, and the uniform and insignia rules that exist to prevent confusion with law enforcement. It then sets out the actual scope of a private officer's authority, which is ordinary private-citizen authority plus a narrow merchant's detention privilege plus whatever the property owner has delegated, and works through each element of that privilege as it is litigated. It covers the state-action doctrine that converts some private guards into constitutional defendants, the surveillance statutes that generate criminal exposure for investigators, and the Fair Credit Reporting Act obligations that attach to background work. Separate parts address employment law inside the industry, negligent security from both sides, insurance and the assault and battery exclusion, investigative engagement and privilege, records and retention, and the emerging areas of remote guarding, analytics, body cameras, and data security.