I get asked this a lot, usually by someone who’s either found something they shouldn’t have, or is thinking about buying something they probably shouldn’t use. So let’s clear it up: yes, you can walk into a shop or go online right now and buy a listening bug, a hidden camera, a GPS tracker, or an app that monitors a phone. None of that is illegal to buy. But whether you’re actually allowed to use it on someone is a completely different question, and the answer is a lot stricter than most people expect.
Here’s the legal picture as I understand it and apply it in my work, including the laws that matter and when you’re on the right or wrong side of them.
It’s All About How You Use It
The law in the UK doesn’t stop anyone making, selling, or buying most surveillance gear. What it does stop is using that gear in a way that breaches someone’s privacy, intercepts their private communications, or amounts to harassment or stalking. The exact same camera that’s perfectly fine on your own front door becomes a crime the moment it’s used to secretly watch someone without their knowledge.
The Laws That Actually Matter Here
The Investigatory Powers Act 2016. This covers intercepting communications in the UK — listening in on calls or reading messages as they’re being sent, without everyone involved agreeing to it, is a criminal offence. This is exactly why phone monitoring apps that grab messages or calls in real time are a problem.
The Computer Misuse Act 1990. It’s a criminal offence to get into someone’s computer or phone without permission. So if you install tracking software on someone else’s phone without them knowing, that’s unauthorised access — and it doesn’t matter what your relationship with them is.
The Protection from Harassment Act 1997. This law, updated to cover stalking, treats monitoring someone — by any method, including electronic devices — as a form of stalking. Using a hidden device to track someone’s movements or activity can land you with a stalking charge, and the penalties for that are serious.
The Voyeurism (Offences) Act 2019. It’s a criminal offence to set up or use equipment to watch someone doing something private without their consent. A hidden camera in a bedroom or bathroom, used to watch someone without their knowledge, is a crime under this law — no exceptions.
UK GDPR. Any personal data gathered through surveillance has to have a proper legal basis for being collected. Secretly watching or recording someone for private reasons, with none of the recognised legal justifications in place, breaks data protection law.
Where You’re On Safe Ground
Using surveillance devices is fine when it’s done properly, with consent where it’s needed, and within the limits of the law. Good examples: a visible CCTV system on your own property, where people can see it’s there; a baby monitor in your own home; a parental monitoring app on your child’s phone, used proportionately and with the child aware of it; and security cameras pointed outward from your own house.
Recording a conversation you’re actually part of is generally fine. Recording a private conversation between two other people, where you’re not involved at all, is much greyer territory.
Where You’re Breaking the Law
Putting a hidden listening device in someone else’s home without them knowing. Installing tracking software on another adult’s phone without telling them. Sticking a GPS tracker on a car that isn’t yours. Hiding a camera in a bedroom or bathroom to watch someone without their consent. All of these break the law, and depending on the circumstances, any one of them could be a criminal offence under the laws I’ve just covered.
And just because a device is sold as something innocent, or sits on a shelf in a normal shop, doesn’t make using it for any of the above legal. What matters is what you intended to do with it and how you actually used it — not how it was marketed to you.
Found a device you think shouldn’t be there, or worried someone’s watching or listening to you? Get in touch with ARF Private Investigators. I’ll give you straight advice and can carry out a confidential sweep.