You can legally hire a private investigator to follow someone in all 50 states, provided the investigator sticks to public places and uses lawful methods. The rule that governs the whole arrangement is simple: anything a person does in plain view of the public can be observed and recorded, but the moment surveillance crosses into spaces where someone reasonably expects privacy, it becomes illegal. Everything else about hiring a PI, from what you pay to whether the evidence will hold up, flows from that line.
What a PI Can Legally Do When Following Someone
A licensed private investigator has roughly the same legal rights as any other private citizen. The professional advantages are training, database access, and the ability to run surveillance without being spotted. Within those limits, an investigator you hire can:
- Follow the subject on foot or by vehicle through public spaces, including sidewalks, roads, parking lots, restaurants, and stores.
- Photograph and video-record the subject from any public vantage point. Visual recording in public requires no consent.
- Pull public records: court filings, property deeds, business registrations, arrest records, and marriage and divorce records. A surprising share of investigative work is desk research.
- Review and screenshot anything posted to a public social media profile.
- Interview neighbors, coworkers, and acquaintances who agree to talk, as long as the investigator identifies themselves honestly.
- Obtain personal information from state DMV databases for purposes the federal Driver’s Privacy Protection Act permits.1Office of the Law Revision Counsel. 18 USC 2721 – Prohibition on Release and Use of Certain Personal Information From State Motor Vehicle Records
No badge, warrant, or special authority is involved. If a private citizen could lawfully do it, so can the investigator you hired.
What a PI Cannot Do
A private investigator is not law enforcement. They cannot detain anyone, conduct a search, or force anyone to answer questions. The hard limits break down into a few categories, and these are where investigators and the clients who direct them get into real trouble.
No Trespassing or Hidden Cameras in Private Spaces
An investigator cannot enter a home, yard, private office, or vehicle without permission, and cannot place recording devices in any location where a person reasonably expects privacy, such as a residence, a hotel room, or a bathroom.2Legal Information Institute. Expectation of Privacy Climbing a fence to look through a window is a crime, whatever the professional purpose.
No Intercepting Private Communications
Federal law makes it a crime to intentionally intercept a private phone call, in-person conversation, or electronic communication, with penalties of up to five years in prison.3Office of the Law Revision Counsel. 18 USC 2511 – Interception and Disclosure of Wire, Oral, or Electronic Communications Prohibited States add their own layer. Some require only one party to a conversation to consent to recording; others require every party. An investigator recording a conversation they aren’t part of, without consent, violates federal law and most state laws.
GPS Tracking Rules Vary by State
This is the area where investigators most often misjudge the law. At least 26 states and the District of Columbia have statutes restricting the use of tracking devices on someone without their knowledge.4National Conference of State Legislatures. Private Use of Location Tracking Devices: State Statutes Some fold GPS tracking into their stalking laws, some target vehicle tracking specifically, and some ban electronic tracking of movements broadly. A few exempt licensed investigators; most do not. Penalties range from misdemeanor fines to felony prison time. If you want a tracker placed on a vehicle, ask your investigator to walk you through the specific statute in your state before anything is attached to anything.
No Impersonating Police
Posing as a police officer, federal agent, or any government official to pull information is a federal crime carrying up to three years in prison.5Office of the Law Revision Counsel. 18 USC 912 – Officer or Employee of the United States A legitimate investigator identifies themselves as a private investigator when asked directly.
No Pretexting for Financial or Protected Records
Federal law prohibits obtaining a person’s financial records by making false statements to a bank or financial institution, and also prohibits asking someone else to do that pretexting on your behalf.6Office of the Law Revision Counsel. 15 USC 6821 – Privacy Protection for Customer Information of Financial Institutions Bank statements, account balances, and transaction histories require a subpoena or the account holder’s written consent. Medical records, phone logs, tax returns, and sealed court files require a court order or the subject’s explicit consent. Any investigator who claims they can pull these without authorization is either lying about their methods or planning to break the law.
When Surveillance Becomes Stalking
There’s a legal line between surveillance and stalking, and it turns on intent and effect. Legitimate surveillance documents public activities for an investigative purpose. Stalking is a course of conduct meant to harass, intimidate, or cause fear.
Federal stalking law makes it a crime to engage in conduct that places a person in reasonable fear of death or serious injury, or causes substantial emotional distress, when done with the intent to harass or intimidate.7Office of the Law Revision Counsel. 18 USC 2261A – Stalking Every state has its own version. An investigator who repeatedly shows up at someone’s workplace, follows them aggressively enough to feel threatening, or continues after being told to stop risks crossing that line. Experienced investigators rotate personnel and maintain distance precisely to avoid it.
This matters to you as the client. If your real purpose is to intimidate an ex-partner rather than to gather evidence for a legal proceeding, both you and the investigator can face stalking charges. Courts look at the purpose and pattern of the surveillance, not just the individual acts.
Your Liability as the Person Who Hired Them
Hiring a licensed PI does not expose you to criminal liability by default. The investigator is an independent contractor. If they independently decide to break the law during an investigation, you are generally not responsible for their choices.
That protection disappears the moment you direct, encourage, or knowingly benefit from illegal conduct. Tell an investigator to break into your ex’s apartment, hack their email, or record their calls in a two-party consent state, and you can be charged as a co-conspirator. “I didn’t know they’d actually do it” is not a defense when the instruction is documented. Civil exposure runs alongside the criminal risk. Courts have allowed invasion-of-privacy and intentional-infliction-of-emotional-distress claims against both the investigator and the client who hired them.
The practical safeguard is a written contract that defines the scope of the work and requires every method to comply with applicable law. When an investigator offers to get something that sounds private, ask exactly how. If the answer involves records obtained without a subpoena or consent, end the conversation.
Will the Evidence Hold Up in Court
Evidence a private investigator gathers is admissible, but only if it was collected lawfully and the chain of custody is intact. The Fourth Amendment’s exclusionary rule technically applies only to government agents, so a judge will not automatically throw out evidence just because a private citizen gathered it. But evidence obtained through trespassing, illegal recording, or hacking still gets excluded under state evidence rules, and both the investigator and client remain exposed to separate criminal liability for how they got it.
To be admitted, the evidence has to be authenticated. Someone with direct knowledge must testify that the evidence is what it claims to be. For surveillance video, that usually means the investigator takes the stand and explains when, where, and how the footage was captured.8Legal Information Institute. Federal Rules of Evidence Rule 901 – Authenticating or Identifying Evidence Any sign that video was edited, photos altered, or records modified after collection can sink the whole package. Detailed contemporaneous notes kept as part of the investigator’s regular work may qualify as business records or present sense impressions under the hearsay exceptions.9Legal Information Institute. Federal Rules of Evidence Rule 803 – Exceptions to the Rule Against Hearsay Plan on the investigator being available to testify; handing a written report to your attorney and expecting it to carry the day rarely works.
What It Costs
Fees depend on the type of work, the investigator’s experience, and the market. Straightforward surveillance generally runs $85 to $150 per hour. Complex or specialized investigations run $150 to $250 per hour or more. A team of investigators working simultaneously can push the hourly rate to $250 to $350 or more.
Most firms require an upfront retainer. A basic case typically runs $1,000 to $3,000. Complex matters require $3,000 to $5,000, and long-term or corporate investigations can start at $5,000 to $10,000 or more. The retainer draws down against hourly charges, and you should expect an accounting of how the money was spent.
Be cautious with unusually low rates. Someone offering $30 an hour for surveillance is likely inexperienced, unlicensed, or willing to cut corners that make the findings useless in court. A cheap investigator who gets caught trespassing or whose evidence gets excluded ends up costing more than a competent one at market rate.
How to Vet the Investigator Before You Hire
About 45 states and the District of Columbia require private investigators to hold a state-issued license. A few states have no state-level requirement, though some of those license at the local level. Verify the license through your state’s regulatory agency; most states run a searchable online database that shows license status and any disciplinary history.
Ask for proof of professional liability insurance and general liability coverage. If an investigator cannot produce current licensing and insurance, that alone is reason to pass, regardless of how experienced they say they are.
Then ask about process. A competent investigator will be candid about what they can and cannot legally do, and will not promise outcomes that would require breaking the law. Anyone who guarantees they can get bank records, phone logs, or access to a private email account is either planning to commit a crime or lying about what they will deliver. You do not want to be their client when the case comes apart.