What Can a Private Investigator Do Legally?

What can a private investigator do legally? Hollywood has a lot to answer for regarding the general public’s understanding of what private investigators do. There’s something about our industry that seems to have captured the imagination of screenwriters across the world. While not entirely far-fetched, these films tend to misrepresent some aspects of our work.

Hollywood Portrayals of PIs

Consider everyone’s favourite fictional private detective, Magnum, PI. In the very first episode of the series, Magnum trespasses on private property and steals a Ferrari, so is it any wonder where the misconceptions about private investigations come from? Granted, it makes for excellent watching, but if Magnum existed, he’d be in jail.

The cast of Mangum, PI (1980)

Because the image of fictional PIs like Magnum is so enduring, it contributes to the mistaken belief that we can or will engage in illegal activity for the greater good of the case. Conducting an investigation isn’t a legitimate excuse for breaking the law. 

What Private Investigators Can't Legally Do

Hollywood often gets it wrong about what private investigators can do legally. To demonstrate our point, let’s look at how these portrayals have translated into real-life misunderstandings about PIs and some responsible alternatives that good detectives should offer. 

Phone and Computer Hacking

Since this is a question that we get asked a lot, let’s address it first. PIs can’t hack someone’s mobile phone or computer without their permission. Obviously, getting this permission would usually defeat the purpose.

It’s illegal for anyone to hack a mobile phone, even the police. Additionally, anyone who attempts to is looking at a £2,500 fine and up to two years in prison. Don’t get involved with PIs who offer phone hacking as a service.

What we can do: If you bring a PI a phone, laptop, or computer with the password, then they might be able to examine it. The search can include recovering deleted photos, text messages, and call logs. We offer services to track mobile numbers and find people through their phone numbers alone.

Accessing Personal Information

The same data protection laws apply to PIs as they do to anyone else. These legal restrictions mean that they can only access consensual, publicly available data. Because of this, PIs can’t look at personal data like bank records, telephone logs, text messages, and location tracking without the owner’s permission.

What we can do: Some publicly available databases, like the electoral roll, have an access fee, and good PIs should have paid it. They should also be able to examine open-source information and social media accounts.

Making Arrests

Private investigators are not usually allowed to make arrests. Some circumstances would allow ordinary civilians to make an arrest, called a ‘citizen’s arrest’, but the legalities of this are complicated.

What we can do: Conducting a citizen’s arrest is dangerous. Therefore, if we witness a crime being committed, it’s almost always a better, safer idea to call the police. 


Just like anyone else, PIs can’t enter private property without the owner’s permission. To be clear, trespassing includes entering other people’s homes, offices, business premises, and storage facilities. 

What we can do: It’s entirely legal for PIs to conduct surveillance in public spaces. This includes taking photographs and following people. GPS vehicle tracking is also a viable option in many cases.

Good private investigators don’t break the law because they don’t need to. They can obtain the information that they require legally. It turns out that what makes a good PI and what makes good TV are pretty much exact opposites.

So Why Hire a Private Investigator?

Now we’ve looked at what a private investigator can do legally, why would anyone hire one? People look to private investigators for help with things that fall outside of the police’s jurisdiction. Typically, the police only get involved if a crime has been committed, so they can’t help you with interpersonal disputes or allegations of employee misconduct.

Private investigators are ordinary members of the public, who have the same legal powers as anyone else. This means they also have the same access to information. You might then ask yourself, ‘what’s the point of hiring a private investigator if I could just do it myself?’

To this, we’d answer that you hire a private investigator for the same reasons you hire any other professional to do a job: convenience, quality, and efficiency. Good PIs promptly gather concrete, useable evidence without you having to lift a finger.

Private Investigations UK operates a network of professional investigators. If you need safe, legal service from a qualified detective, give us a call on 0800 002 9858. You’ll get friendly advice and a free 30-minute consultation. Alternatively, please send us a message, and one of our agents will get back to you today.

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