Instructing a Private Investigator: What a Solicitor Can Lawfully Ask For

Instructing a Private Investigator: What a Solicitor Can Lawfully Ask For

A private investigator can be a valuable part of a litigation team, gathering evidence a solicitor cannot obtain from the desk. The value only holds, though, if the work is done lawfully and the resulting evidence survives scrutiny in court. Instructing one well means understanding what they may do, what they must not do, and how their findings are recorded and presented so they help the case rather than harm it. Getting that wrong can turn a useful line of enquiry into a liability, and can hand the other side an easy argument about how the material was obtained.

What a Private Investigator Can and Cannot Do

There is no general licence that entitles an investigator to break the law. Locating a person, confirming a current address, carrying out open source research and conducting proportionate observation from public places are legitimate activities. Obtaining personal data by deception, often called blagging or pretexting, is a criminal offence under data protection law, as is unlawfully accessing accounts, devices or private communications. Trespass, harassment and covert recording inside private premises all carry legal risk and can taint the wider case. A reputable investigator processes personal data under a lawful basis, usually legitimate interests, and can explain the balancing assessment that sits behind that basis if it is ever questioned.

The ABI Code and Professional Standards

The Association of British Investigators operates a code of conduct, and its members work to a data protection code of conduct that has been approved by the Information Commissioner. Instructing a firm that follows recognised standards gives a solicitor a defensible answer if the other side asks how information was obtained. It also reduces the chance of commissioning something that later has to be disclosed as improperly gathered. Asking about professional membership, indemnity insurance and data protection compliance at the outset is sensible due diligence, and a serious firm will expect those questions and answer them without hesitation.

Using a Private Investigator’s Evidence in Court

Evidence is only useful if it is admissible and proportionate. Surveillance footage and open source material should be captured in a way that preserves its integrity, with clear records of when, where and how it was obtained, so it can be authenticated later. The court weighs relevance and proportionality, and material gathered by unlawful means can be excluded or can damage the credibility of the party who relied on it. A well briefed investigator produces a witness statement and exhibits that stand up under cross examination, rather than a bundle of images with no explanation of their provenance. That discipline is often what separates evidence that is accepted from evidence that is challenged.

Common Mistakes When Instructing an Investigator

The frequent errors are asking for a result rather than a lawful process, giving no written scope, and failing to record the lawful basis for the work. Instructing at the last minute leaves no time to gather clean evidence, and vague instructions invite an investigator to improvise. A clear letter of instruction, a defined and proportionate task, an agreed budget, and a firm that documents its methods will avoid most of the problems that see investigation evidence challenged or thrown out. Treat the instruction as carefully as you would any other step that has to hold up in front of a judge, because in practice that is exactly what it is. A short conversation about scope and lawful basis at the start saves a great deal of argument later.

If you are considering investigation support for a case and want it done to a standard the court will accept, fill in the form below to get in touch with the Tremark team.

Frequently Asked Questions

Is it legal to instruct a private investigator?

Yes. Instructing one is lawful, provided the work itself is carried out within the law and any personal data is processed under a proper lawful basis and to a proportionate extent.

Will a private investigator’s evidence be accepted in court?

It can be, where it is relevant, proportionate and lawfully obtained, and where its integrity has been preserved so it can be authenticated. Evidence gathered unlawfully risks being excluded.

What should a letter of instruction cover?

It should define the task, set proportionate limits, confirm the lawful basis for processing data and ask the investigator to record their methods, so the work can be explained and defended later.

Useful sources: the Association of British Investigators, the Information Commissioner’s Office, and the Data Protection Act 2018. See our page on private investigators in the UK and our ABI code of conduct guide for solicitors.