Is It Illegal to Put Spyware on Your Partner's Phone? What the Law Says

You have the phone in your hand. You know the passcode. Installing an app would take a few minutes, and you would finally know what is going on. And yet something makes you stop and search first: is this actually legal?

It is the right question to ask, because the answer surprises a lot of people. Being married, owning the phone or paying for the plan does not change it much.

This guide covers what the law says about putting spyware on a partner's or spouse's phone in the US, the UK, Canada and Australia, what has happened to people and companies involved, whether the evidence helps in a divorce, and what you can legally do instead.

This is general information, not legal advice. Laws vary between countries and, in the US, between states. If you are considering legal action or divorce, talk to a lawyer where you live.

What counts as spyware here

This guide is about apps installed on another adult's phone to watch it secretly: reading messages, logging what is typed, recording the screen, tracking location, or pulling data from their cloud account. Security researchers call this category stalkerware: software that lets someone monitor a device remotely without the user's consent and without a persistent notification.

The legal question is the same whatever the app is called, whether it is sold as "monitoring", "parental control" or "catch a cheater". What matters is what it does and whether the person using the phone agreed to it. If you want to know how these apps work in practice and what each type really shows, we review them in our guide to spy apps to catch a cheater.

The short answer

In most places, installing spyware on another adult's phone without their consent is illegal, and being married to them does not change that. Owning the device or paying for the phone plan generally does not either. The person whose communications are captured is the one whose consent counts.

United States

• The federal Wiretap Act (18 U.S.C. § 2511) makes it a crime to intentionally intercept someone's electronic communications without authorization, punishable by up to five years in prison, plus fines.

• The same law lets the victim sue (18 U.S.C. § 2520): actual damages or statutory damages of $100 a day of violation or $10,000, whichever is greater, plus punitive damages and attorney's fees.

• Marriage is not an exception. In Glazner v. Glazner (2003), the full federal appeals court for the Eleventh Circuit held that the federal wiretap law contains no exception for spouses.

• States add their own laws on eavesdropping, unauthorized computer access and electronic tracking, some of them stricter than federal law, and some requiring the consent of everyone in a conversation before it can be recorded.

United Kingdom

Intercepting someone's communications without lawful authority is an offence under the Investigatory Powers Act 2016. Accessing someone's device without permission can also fall under the Computer Misuse Act 1990, and prosecutors have used harassment law in stalkerware cases.

Canada

Section 184 of the Criminal Code makes wilfully intercepting a private communication an offence punishable by up to five years in prison.

Australia

Surveillance devices and computer access are regulated state by state. Across the country, secretly installing software to monitor another adult's device can breach surveillance, telecommunications or computer offence laws.

"But it's my phone" and other common exceptions

"I bought the phone" or "it's on my plan." Ownership of the device or the account generally does not authorize you to intercept the communications of the adult who uses it. Consent comes from the user, not the bill payer.

"We're married." Federal courts in the US have rejected a marital exception to wiretap law, and none of the other countries above treat marriage as consent.

"They gave me their passcode once." Knowing a passcode is not the same as permission to install software or read their messages. Mexico's Supreme Court, for example, rejected emails a spouse obtained with a password that had been shared earlier in the relationship.

"They agreed to share locations." Consent to one thing, like location sharing you both set up, is not consent to having messages read or keystrokes logged.

"It's for our kids' safety." Monitoring software sold for parents is meant for a minor's device. Using it on another adult does not become legal because of how it is marketed.

What happens to people and companies involved

• Individuals get sued. The civil damages in the US Wiretap Act exist so that the person spied on can take the person who did it to court. In a divorce, the spying can become the story instead of the affair.

• Regulators have shut spyware makers down. In 2021, the US Federal Trade Commission banned a stalkerware company and its CEO from the surveillance business entirely, its first outright ban of this kind. In 2019, it had already barred another maker from selling its monitoring apps unless used for legitimate purposes.

• Founders have been prosecuted. In January 2026, the founder of a spyware company whose ads targeted people who wanted to "catch a cheater" pleaded guilty in US federal court to charges including hacking and selling surveillance software for illegal use.

• The data leaks. Everything these apps collect sits on the vendor's servers, and several vendors have been breached, exposing both the monitored people's data and their customers' identities. A leak can make public exactly who was spying on whom.

Does spyware evidence help in a divorce?

Rarely, and it can hurt you.

• You do not need to prove adultery to divorce. Every US state allows no-fault divorce; New York was the last to adopt it, in 2010. England and Wales introduced no-fault divorce in 2022. Canada and Australia grant divorce on the basis of separation or breakdown of the marriage.

• Illegally obtained evidence is often excluded, and the way you obtained it can be raised against you, in the divorce, in custody discussions, or in a separate lawsuit.

• It can be used against you. Secretly monitoring a partner's phone is widely recognised as a form of controlling behaviour, and it can be raised in requests for protective orders.

What decides most divorces is money, property and children. A family lawyer can tell you what evidence matters for those, and how to obtain it legally, before you do anything you cannot undo.

What you can legally do instead

None of these give you someone's private messages. They do give you facts you are allowed to have.

• Check whether they have an active dating profile. A dating profile search looks at dating profiles that any user of the app could see. CheatEye searches from a first name, an approximate age, a location and an optional photo, across Tinder and, with its network extension, Bumble, Hinge, Happn and OkCupid. It does not touch their phone and does not notify them.

• Search their face online. A reverse image search on Google Images, TinEye and Yandex can reveal a second social media account or a profile under another name.

• Look at what is already yours. A joint bank account, bills in both your names, what they post publicly.

• Use the free, legal methods first. We list them in our guide to websites to catch cheaters.

• Talk to a lawyer before you act, especially if you are married, share property or have children.

• Consider a licensed private investigator if you need evidence for court. They know what they are legally allowed to collect where you live.

FAQ

Is it illegal to put a spy app on my spouse's phone?

• In most places, yes. In the US, intercepting someone's communications without consent can violate the federal Wiretap Act, and federal courts have rejected the idea that marriage is an exception. The UK, Canada and Australia have similar laws.

Is it legal to put spyware on a phone I own?

• Owning the phone generally does not make it legal to intercept the communications of the adult who uses it. The consent that matters is the user's.

Is it legal if my partner agrees?

• Monitoring with the informed consent of the adult using the phone is a different situation from secret monitoring. Consent to one thing, such as sharing locations, does not extend to reading messages. If you rely on consent, make sure it is explicit, and get legal advice.

Can I use evidence from a spy app in court?

• It is often excluded, and using it can expose you to criminal charges or a lawsuit. Talk to a family lawyer before relying on anything collected from someone else's phone.

What happens if you get caught spying on your partner's phone?

• Depending on where you live, criminal charges under interception or computer access laws, a civil lawsuit for damages, and consequences in divorce or custody proceedings. Protective orders are also possible.

How can I find out if my partner is cheating legally?

• Check for an active dating profile with a profile search, run a reverse image search of their photos, look at information you legitimately share, and speak to a lawyer or licensed investigator if you need evidence for court.