Is It Legal to Hire a PI to Follow Someone?

Published August 7, 2026

If you suspect a spouse of cheating, worry about an employee committing fraud, or need to locate someone who owes you money, you may have wondered: is it even legal to hire a private investigator to follow someone? The short answer is yes — in most circumstances, hiring a licensed PI to conduct surveillance is completely legal. But the longer answer matters just as much, because the legality depends heavily on who is being followed, where, how, and why.

What Makes PI Surveillance Legal?

Private investigators are trained professionals who gather information using legal methods. The cornerstone of lawful surveillance is the concept of a reasonable expectation of privacy. As a general legal principle — well established in U.S. courts — people do not have a reasonable expectation of privacy in public spaces. This means a PI can legally:

• Observe and photograph a person in a public place such as a street, parking lot, or park
• Follow a subject in a vehicle on public roads
• Document activity that is visible from a public vantage point
• Record video of someone who is in plain public view

Because these activities occur where anyone could observe the same things, they generally fall within the law. A licensed PI is essentially doing what any observant member of the public could do — but with professional training, experience, and proper documentation.

You can review general legal definitions around privacy and surveillance at the Cornell Legal Information Institute, which provides plain-language explanations of relevant statutes and case law.

What Private Investigators Cannot Legally Do

A legitimate, licensed private investigator must operate strictly within the law. There are clear boundaries — and crossing them exposes both the PI and potentially the client to criminal or civil liability. Lawful investigators cannot:

• Trespass on private property to conduct surveillance
• Wiretap or record private phone calls without the consent required by state or federal law
• Hack into email, social media, or devices — this is a federal crime under the Computer Fraud and Abuse Act
• Impersonate a law enforcement officer or claim authority they do not have
• Access protected records illegally, such as financial records, medical records, or sealed court files, without proper authorization
• Place a GPS tracker on a vehicle in states where doing so without consent or a court order is prohibited — laws vary significantly by state
• Use pretexting (lying about their identity) in ways that violate federal or state law

If a PI offers to do any of these things, that is a serious red flag. Reputable investigators decline illegal requests even when a client believes the ends justify the means. For guidance on consumer protections related to background investigations, the Federal Trade Commission publishes helpful resources on what investigators and data brokers can legally do.

Licensing Requirements Vary by State

Private investigator licensing is regulated at the state level, and the rules differ considerably depending on where you are. Most states require PIs to hold an active license, carry a surety bond or insurance, and meet minimum training or experience requirements. Some states require a background check and even a written examination.

In Texas, for example, private investigators must be licensed through the state's licensing authority, and operating without a license is a criminal offense. Texas law also sets specific rules around electronic surveillance and the use of tracking devices. If you are hiring a PI in Texas, always verify their license status through the appropriate state agency before signing any agreement.

No matter where you are, you can start a licensing verification search through USA.gov's directory of state government agencies, which can point you toward your state's specific licensing board.

Common Legitimate Reasons People Hire a PI for Surveillance

People hire private investigators to conduct lawful surveillance for many valid reasons, including:

• Suspected infidelity in a marriage or domestic partnership
• Child custody disputes where a parent suspects unsafe behavior
• Insurance fraud investigations (often conducted by or on behalf of businesses)
• Locating a missing person or someone who has skipped on a debt
• Verifying that an employee is truthfully reporting an injury or absence
• Due diligence before a major business transaction or partnership

In each of these cases, the client has a legitimate purpose, and a licensed PI gathers factual information through legal observation. That evidence can then be used in legal proceedings, negotiations, or personal decision-making.

The Line Between Surveillance and Stalking

It is worth understanding one important boundary: hiring a PI to harass, intimidate, or stalk someone is not legal. Even if the activity happens in public, following someone relentlessly for the purpose of causing fear or harm can constitute criminal stalking under both state and federal law. A reputable PI will decline work that appears designed to harm a subject rather than gather factual information for a lawful purpose.

If you are unsure whether your intended use of surveillance evidence could create legal complications — particularly in custody cases, divorce proceedings, or civil litigation — it is strongly advisable to consult a licensed attorney before hiring a PI. An attorney can help you understand what evidence will actually be admissible and what approach best supports your case. General information on privacy law and evidence is available through Nolo's legal guides, which cover a wide range of civil and family law topics in plain language.

Practical Steps Before You Hire a PI

If you decide that hiring a private investigator is the right move, here are concrete steps to protect yourself and get the best outcome:

1. Verify the PI's license. Ask for their license number and check it with your state's licensing board.
2. Ask about their specific experience. A PI who specializes in domestic cases is different from one who focuses on corporate fraud.
3. Get a written contract. It should specify the scope of work, the methods to be used, fees, and how findings will be delivered.
4. Ask how they handle legally sensitive situations. For example: "What do you do if surveillance requires entering private property?" A good PI will tell you clearly that they won't.
5. Understand what the evidence can be used for. Confirm with both the PI and, where relevant, an attorney how the findings can be used legally.
6. Never ask a PI to break the law. Doing so could expose you to civil or even criminal liability.

What a PI Can Promise — and What They Cannot

A professional private investigator can promise diligent, lawful effort. They cannot guarantee any particular result. Surveillance may confirm your suspicions, or it may not. Evidence may be inconclusive. A trustworthy investigator will be honest with you about this reality upfront rather than promise outcomes they cannot deliver.

If you are ready to explore your options, you can use this site to request a connection with a licensed private investigator in your area — it's free, with no obligation, and a simple way to ask questions and get a sense of what professional surveillance work would involve in your specific situation.