Hiring a private investigator to follow someone is legal in most situations, provided the investigator is licensed in states that require it and sticks to lawful methods. A PI can tail a person on public streets, photograph them in public places, and watch a home from the sidewalk without anyone’s permission. The question is not whether following is allowed, but where the investigator goes, what tools they use, and why you hired them in the first place. Any of those three can turn a lawful investigation into a crime for the PI, for you, or for both.
What a Licensed PI Can Legally Do
Following a person is the core of the work, and from public spaces it requires no consent and no court order. A PI can sit in a parked car outside a business, record someone walking down a street, photograph a meeting on a park bench, and document interactions that happen in plain view. You have no legally protected expectation of privacy when you’re out in public, and neither does the person being watched.
Beyond physical surveillance, investigators pull from public records anyone could access with time and know-how: court filings, property records, business registrations, voter rolls, and open criminal history databases. Licensed PIs also reach certain restricted sources. Under the Driver’s Privacy Protection Act, a licensed investigator can obtain personal information from state motor vehicle records for purposes the statute permits, including investigation in anticipation of litigation and insurance claims work.
This is why PIs are useful in custody disputes, insurance fraud investigations, litigation preparation, and locating missing people. The reach is wide, but it has edges.
Public vs. Private: Where the Line Sits
Courts separate lawful surveillance from illegal snooping by asking whether the person being watched had a reasonable expectation of privacy. On a street, a highway, in a restaurant, or in a store, the answer is no. Record away. Inside a home, in a bathroom, in a doctor’s office, or behind a fence on private property, the answer flips. An investigator who defeats that expectation through trespass, hidden cameras, or wiretapping has crossed into criminal territory, and the reason for the hire doesn’t change that.
Verify the License Before You Hire
Private investigation is a regulated profession in roughly 43 states. The rest handle it at the city level or not at all. Before you sign anything, check license status through your state’s regulatory agency. An unlicensed investigator working in a state that requires a license is already breaking the law, which can taint any evidence they gather and pull you into liability you didn’t sign up for. Most states keep a searchable database online.
Methods That Turn a Legal Hire Into a Crime
Even a licensed PI working a legitimate case can commit serious crimes if their tactics go too far. These are the lines that matter.
Trespassing
A PI cannot enter private property without permission. Climbing a fence, walking into a backyard, slipping into a home, apartment, or private office — all trespass. The fact that a spouse, employer, or insurer hired the investigator does not create a right to be on someone else’s property. Surveillance has to happen from somewhere the investigator has a legal right to stand.
Wiretapping and Intercepting Communications
Federal law makes it a crime to intercept phone calls, emails, texts, or other electronic communications without authorization. Under the Electronic Communications Privacy Act, intentionally intercepting private communications, or getting someone else to do it, carries up to five years in federal prison.1Office of the Law Revision Counsel. 18 USC 2511 – Interception and Disclosure of Wire, Oral, or Electronic Communications Prohibited Federal law allows one-party consent, but about a dozen states require every party to a conversation to consent before it can be recorded, so the state where the recording happens drives the analysis. Tapping a line, pulling voicemails, or intercepting email without proper authorization is a federal felony.
Hacking Accounts
Breaking into email, social media, cloud storage, or any computer system is illegal under the Computer Fraud and Abuse Act. A first offense for unauthorized access carries up to one year in prison, rising to five years when the access is for commercial gain or in furtherance of another crime, which covers most PI hacking scenarios.2Office of the Law Revision Counsel. 18 USC 1030 – Fraud and Related Activity in Connection with Computers Handing a PI your spouse’s password doesn’t fix this. Accessing an account without the account holder’s authorization is still a violation regardless of how the login was obtained.
Impersonating Law Enforcement
A PI who flashes a fake badge, claims to be a police officer, or poses as a government official to extract information commits a federal crime punishable by up to three years in prison.3Office of the Law Revision Counsel. 18 USC 912 – Officer or Employee of the United States It’s a tempting shortcut and a felony every time.
Pretexting for Financial Records
The Gramm-Leach-Bliley Act targets “pretexting,” using false statements, forged documents, or impersonation to trick banks and other financial institutions into releasing customer information. Calling a bank while pretending to be the account holder, or submitting fake authorization forms, violates federal law.4Office of the Law Revision Counsel. 15 USC 6821 – Privacy Protection for Customer Information of Financial Institutions Penalties run up to five years in prison for a standard violation and up to ten years when the pretexting is part of a pattern of illegal activity involving more than $100,000 in a twelve-month period.5Office of the Law Revision Counsel. 15 USC 6823 – Criminal Penalty
Protected Records
Several federal statutes seal off categories of records a PI cannot lawfully pull without proper authorization. Medical information is protected under HIPAA, which gives individuals the right to control who sees their health records and restricts disclosure by providers and insurers.6U.S. Department of Health & Human Services. Individuals’ Right Under HIPAA to Access Their Health Information 45 CFR 164.524 Student records are protected under FERPA.7U.S. Department of Education. Joint Guidance on the Application of FERPA and HIPAA to Student Health Records A PI who uses deception, bribery, or unauthorized access to obtain any of these exposes both the investigator and the client to prosecution and civil suit.
Stalking and Harassment
Surveillance can become stalking when the conduct causes the subject genuine fear or substantial emotional distress. Federal law criminalizes a course of conduct intended to harass or intimidate someone that places them in reasonable fear of serious bodily injury or causes substantial emotional distress.8Office of the Law Revision Counsel. 18 USC 2261A – Stalking Every state has its own stalking statute as well. Following too closely, making repeated unwanted contact, or showing up at the subject’s workplace to intimidate can produce charges under both. Experienced investigators keep distance precisely because this line is enforced.
GPS Tracking Has Its Own Rules
GPS trackers are a frequent client request and one of the easiest ways to get into trouble. At least 26 states and the District of Columbia have passed laws on the private use of location tracking devices. Nine flatly prohibit installing a tracker on someone else’s vehicle without the owner’s consent. A handful of states, including Texas and Virginia, carve out limited exceptions that allow licensed PIs to use trackers in defined circumstances. In states without a PI exception, placing a tracker on someone’s car is a criminal offense no matter who hired the investigator.9National Conference of State Legislatures (NCSL). Private Use of Location Tracking Devices – State Statutes
If a PI proposes GPS tracking, ask directly whether it is lawful in the state where the vehicle will be driven. Assuming it’s legal because an investigator suggested it is how clients end up as defendants.
When Your Reason for Hiring Makes It Illegal
Even if every method the PI uses is lawful on its own, your purpose can make the hire itself a crime. The law treats client and investigator as separate actors who can each be independently liable.
- Hiring a PI to intimidate, frighten, or psychologically torment someone rather than gather evidence for a legitimate matter can produce stalking or harassment charges against you.
- Instructing a PI to trespass, hack an account, or wiretap communications makes you as liable as the person who carries out the act.
- Hiring an investigator knowing or expecting they will use unlawful methods can be enough on its own to create criminal exposure, even without an explicit instruction.
- Using a PI to surveil or dig up material on an employee who reported illegal activity can qualify as unlawful retaliation under federal whistleblower protections.10U.S. Department of Labor. Whistleblower Protection Programs
- Hiring a PI as part of a scheme to commit insurance fraud, identity theft, or similar financial crimes implicates you in the underlying fraud whether or not the investigator knew.
Hiring a PI is not a shield. If pursuing the goal yourself would be illegal, outsourcing it to a licensed professional doesn’t change that.
What You and the PI Face If Lines Get Crossed
Investigators face immediate professional consequences first. A state licensing board can suspend or revoke a PI’s license for breaking the law or violating the profession’s code of conduct. The criminal and civil exposure runs in parallel and reaches the client too.
Criminal penalties track the specific violation. Trespass and simple harassment are typically misdemeanors carrying fines and up to a year in jail. Illegal wiretapping runs up to five years in federal prison, as does pretexting for financial records. Computer hacking can reach five years for a first offense committed for financial gain and ten years for repeat offenders. Clients who directed or knowingly benefited from illegal methods face the same exposure under conspiracy and aiding-and-abetting theories.
On the civil side, the person who was watched can sue for invasion of privacy, intentional infliction of emotional distress, or defamation if false material was spread. Judgments can be substantial. A client may also be held vicariously liable for the investigator’s torts, which means owing damages for the PI’s wrongful acts even without a direct instruction, particularly where a court finds you negligently selected or supervised the investigator.
Will the Evidence Even Be Usable?
A detail that surprises most people: evidence a private investigator gathered illegally is often still admissible in civil court. The Fourth Amendment’s exclusionary rule, which forces courts to throw out evidence from illegal searches, applies to government agents, not to private citizens. A photograph or recording obtained through an illegal private search can still come in if it is relevant and reliable.
That doesn’t make illegal investigation consequence-free. The PI and the client remain exposed to prosecution and lawsuits over how the evidence was obtained. In criminal cases, courts have more discretion, and evidence tainted by illegal conduct is more likely to be excluded, especially when a private investigator was coordinating with law enforcement. You can win admission of your evidence in a divorce case and still be charged with wiretapping for how you got it.
How to Hire Without Exposing Yourself
A few steps meaningfully reduce the risk. Verify the investigator’s license through your state’s regulatory agency. Get a written contract that defines the scope of the work and states that the investigator will use only lawful methods. Never instruct a PI to do something you know is illegal, and be cautious with any investigator who promises results that sound too good to be true or waves off questions about legal limits.
Ask about methods before the work starts, particularly recording, database searches, and GPS. A competent investigator will know the specific laws of your state and will explain what they can and cannot do. If they won’t have that conversation, hire someone who will. The quickest way to lose a case is to hand the other side a criminal misconduct argument built on your own investigator’s choices.