What a Private Investigator Can and Cannot Do in the UK

Updated 13 October 2026 by Investigation Bureau

A private investigator in the UK has no powers that a member of the public does not have. The work is done through observation, public and licensed records, lawful enquiry and careful evidence handling, and anything that needs access to someone's private communications, accounts, devices or protected records is unlawful for an investigator and worthless as evidence.

The same job can be done lawfully by one firm and criminally by another, and this guide sets out which is which.

If your situation is specific, send a confidential enquiry and we reply within one working day with a plain answer on what is lawful.

The short answer

The law gives private investigators nothing extra: no warrant card, no right of entry, no access to police or government databases and no exemption from the criminal law. What an investigator brings is method: where lawful information sits, how to watch without crossing into harassment, how to handle personal data under UK GDPR and how to turn what is found into evidence a court will accept.

If you want one line to keep: a UK private investigator may do only what any member of the public may lawfully do, but does it with method, records it properly and can stand behind it in court.

What a private investigator can do

Observe and record in public places. Watching, following and filming a person where they have no reasonable expectation of privacy, for a legitimate purpose and in proportion to it.
Trace people from public and licensed data. The open electoral register, Companies House, property and court records, and credit reference data accessed under licence for a permitted purpose such as debt recovery.
Research people and companies from open sources. Public social media, company filings, insolvency records, press archives and the open web.
Background and due diligence checks. With the subject's written consent where the law or the purpose requires it, as in pre-employment screening.
Interview people who agree to talk. Discreet about the client, but never lying about anything material or claiming an official position.
Serve court documents. Process serving is routine work.
Preserve and present evidence. Timestamped video, notes made at the time, exhibits with a chain of custody and a witness statement.
Work with your solicitor. Taking instruction through a solicitor and reporting in a form that fits the proceedings.

What a private investigator cannot do

None of this becomes lawful because a client pays for it, and most of it is a criminal offence for the investigator and the client who asked.

Intercept calls, messages or emails. An offence under the Investigatory Powers Act 2016.
Access accounts, devices or systems without authority. Guessing a password, planting spyware or logging into someone else's account is an offence under the Computer Misuse Act 1990.
Obtain phone, bank, medical or other records by deception or from a contact. Pretending to be the customer, or paying someone on the inside, is an offence under section 170 of the Data Protection Act 2018.
Trespass or enter private property. An investigator has no right of entry anywhere, and anything seen from inside a garden, driveway or stairwell is tainted.
Place a listening device or camera inside someone's home or car. Nobody outside the police and the bodies that hold warrants has a lawful basis for it.
Impersonate police or officials. Claiming to be a police officer is an offence under the Police Act 1996, and posing as any other official to get information is fraud.
Make an arrest beyond the ordinary citizen's power. Investigators have the same narrow power as anyone else under section 24A of the Police and Criminal Evidence Act 1984.
Access police, DVLA or HMRC data. These records are closed, and anyone offering a name from a number plate on the spot is describing a crime or a bluff.
Harass, stalk or confront. Persistent following the subject fears, approaching them or contacting their family is an offence under the Protection from Harassment Act 1997.

The grey areas explained

Some methods are lawful in one setting and criminal in another.

GPS trackers. Lawful only with a documented basis and the authority of the vehicle's owner or keeper. On a spouse's car, or any vehicle the client does not own, a tracker becomes harassment and unlawful processing of personal data. The GPS tracker law guide sets out who may fit what.

Following someone. Observation in public is lawful. Harassment is not, and the line sits in the conduct: following the subject becomes aware of and fears, or that goes beyond any proportionate purpose. Our guide on having someone followed goes through it.

Social media. Anything published to the public may be read, saved and relied on. A fake profile, a friend request under a false name or talking someone into handing over a private account is a different thing.

CCTV. Footage belongs to whoever operates the camera. An investigator may ask for it, and the person filmed may request their own images, but nobody can compel release without a court order or a police request.

Recording conversations. Recording a conversation the investigator is part of is lawful and can be evidence. Planting a device to capture other people's conversation is bugging, and it is not.

Why the limits make the evidence stronger

The limits are the reason the work has value.

Courts in England and Wales can exclude evidence, and the first thing a judge asks about surveillance footage or a tracing report is how it was obtained. Lawful, proportionate material is routinely admitted; material gained by trespass, deception or interception can be thrown out and can hand the other side a claim. Our guide on whether investigator evidence is admissible covers the detail.

Proportionality under UK GDPR works the same way: a lawful basis recorded before starting, no more personal data than the objective needs, and every step explainable afterwards. A result that cannot be explained is not a result.

What to ask before you instruct anyone

Because there is no licence to check, your questions stand in for one.

"What will you refuse to do for me?" A credible firm has a ready answer.
"What is the lawful basis for my case?" You should hear it in plain English, with a reason.
"Who is accountable, and will they give evidence?" A named person who will sign a witness statement.
"Where are you registered?" A company at Companies House and a data controller on the ICO register.

Our guide on how to check a private investigator is legitimate walks through each check, and is it legal to hire a private investigator? explains where the liability sits if methods go wrong.

Investigation Bureau's own position

Investigation Bureau is a trading name of Bureau Nine Ltd, a registered UK company that you can look up at Companies House. We are registered with the ICO as a data controller (ZC259849), which you can confirm on the ICO's public register.

Before any work begins we record the lawful basis, the objective and the methods. Every report sets out how the material was obtained, so a solicitor or a judge can see the method as well as the result.

We refuse interception, hacking, blagging, trackers on vehicles the client does not control, devices inside homes or private cars, impersonation, and any task whose real purpose is to intimidate or to find someone with a lawful reason to stay hidden. If a request is on the wrong side of the line, we say so at once.

Frequently asked questions

Can a private investigator access phone records?

No. Call logs, texts, itemised bills and the content of calls are protected by the Investigatory Powers Act 2016 and the Data Protection Act 2018, and no private investigator has a lawful route to them. An investigator can still work from open sources and from records the client is entitled to hold. Our phone records guide explains the difference.

Can a private investigator find out where someone lives?

Usually, yes, and lawfully, through public records, open-source research and credit reference data accessed under licence for a permitted purpose. The purpose matters: a debtor, a witness, a beneficiary or a lost relative is a legitimate interest. Someone with a lawful reason to stay hidden from the client, such as a former partner protected by an injunction, is not traced.

Is it legal for a private investigator to follow someone?

Yes, provided the surveillance stays in public places, serves a legitimate purpose and is proportionate to it. It becomes unlawful when it tips into harassment under the Protection from Harassment Act 1997: conduct the subject fears, confrontation, or persistence beyond any evidential need.

Can a private investigator put a tracker on a car?

Only on a vehicle whose owner or keeper has authorised it, with the lawful basis documented first: a company fleet vehicle, or a car registered to the client. A tracker on a partner's car, or on any vehicle the client does not own, is unlawful processing of personal data and can amount to harassment, and no professional firm will fit one.

Do private investigators need a licence in the UK?

No. Parliament provided for the licensing of private investigators in the Private Security Industry Act 2001, with the Security Industry Authority to run the scheme, but that part of the Act has never been brought into force. There is no licence to check. A legitimate firm proves itself through the company register, the ICO register and its conduct from the first conversation.

Ask before you act. Tell us what you need to know and we will say plainly whether it can be done lawfully. Send a confidential enquiry and we reply within one working day.

Sister service: Trace Bureau is our fixed-price address tracing service, for anyone who only needs a current UK address for a lawful purpose. Charged only when we find them. Investigation Bureau is a Bureau Nine company.