Powers, Duties, and Restrictions of a Private Investigator
A private investigator is a private citizen with no police powers. The single most tested idea: a PI may observe, document, interview, and report, but may not arrest (except a narrowly defined citizen's arrest available to anyone), search, seize, detain, or compel information. A PI may not impersonate a peace officer or use a badge or title suggesting official authority. Trespass, unlawful entry, and interception of communications remain unlawful regardless of the investigative purpose.
Duties run in two directions. To the client: competence, confidentiality, honest reporting, and avoiding conflicts of interest. To the public and the state: lawful conduct, accurate records, and cooperation with the Bureau. A PI who discovers evidence of a crime may report it but generally cannot withhold evidence from lawful process; a subpoena or court order can compel testimony and records, subject to privilege.
Restrictions to memorize: surveillance may not violate reasonable expectations of privacy (restrooms, dressing rooms, private residences); pretexting to obtain financial records is prohibited by GLBA; obtaining phone records by deception is prohibited; and PIs must avoid harassment and stalking behavior even during surveillance. Detention of a subject is unlawful absent a citizen's arrest basis.
Traps: questions offer a plausible-sounding "PI authority" - e.g., demanding ID, entering property, or pulling someone over. None exist. Another trap is confusing what a PI may do (observe from public space) with what requires consent or a warrant.
Rule of thumb: If a private citizen cannot lawfully do it, neither can a licensed PI - the license adds accountability, not authority.