Posted September 8, 2020
Federal judges in the United States are beginning to push back against police requests for “geofence warrants”, citing constitutional concerns. In this short article, we will introduce you to the problem, tell you what it means for your privacy and explain how you can limit the authorities (and others) to track you.
What is geofencing?
Roughly speaking, geofencing refers to the practice of creating a virtual boundary around a physical area. The technique is often used by marketers and advertisers who want to show more relevant ads or offer tailored suggestions to people in a specific geographic location (for example, by displaying ads or special offers for a nearby business). Geofencing works by using location data retrieved from mobile devices, which can come from a variety of sources, including GPS, Bluetooth, RFID, and Wi-Fi data.
What are geofence warrants?
Geofence warrants (sometimes called “reverse placement searches”
What’s wrong with geofence guarantees?
Geofence warrants are without a doubt a legitimate tool that helps police identify suspects in serious crimes when other investigative avenues have failed. Opponents of reverse location searches point out, however, that they can implicate innocent people in crimes just because someone else used their phone: In 2018, an Arizona man was jailed in a homicide investigation for nearly a week in the exact scenario. There are also serious privacy and legal concerns about the procedure – and this has now been acknowledged by several judges tasked with reviewing geofence warrant requests.
What the law says
Chicago federal court judges recently rejected police requests for geofence guarantees on the grounds that they were too broad and most likely unconstitutional, saying they appeared to violate the probable cause and specification requirements of the fourth amendment. One of the judges made it very clear in his written opinion that the effort went beyond the immediate case, and called on the government’s “undisciplined … overuse” of geofence guarantees as a threat to “our collective sense of privacy and trust in law enforcement. ”.
While these court decisions were seen by many as a victory for privacy, the case has not been decided, and will probably require further judicial review.
How to protect your privacy
Reasonable people may disagree about the legality or desire for law enforcement when using geofence guarantees in criminal investigations. But the debate itself highlights an important privacy implication for everyday mobile users: namely that our phones and tablets give away our location data to any number of apps, services and technology companies.
For you, the good news is that there are some steps you can take to protect your privacy, and in iOS 14 it’s easier than ever to limit how much of your data is shared with third parties:
Deny apps permission to track
In iOS 14, if an app wants to track you, it must first ask. It may be best to say “no” to these tracking requests by default. If you decide to allow an app to access your location or other data in the future, you can always provide this on an app basis in the relevant sections of the Settings> Privacy menu.
Go to to prevent apps from even asking if they can track you Settings> Privacy> Tracking> and switch between Allow apps to request tracking attitude towards Of.
Restrict access to location data
You may not want to completely disable Location Services, but you may want to restrict access to only those apps that really need it, and only when you actually use them.
Go to to see a list of apps and location permissions they have Settings> Privacy> Location services and click on the app you want to inspect. There are three possible location access settings: Never ask next time and while using the app. Rule of thumb: If an app does not have a good reason to access your location, do not share your data.
In addition, iOS 14 only lets you give your apps your approximate location, instead of your exact location. This means that the app will be able to see that you are somewhere in New York, for example, but not that you are on the corner of 5th Avenue and East 58th Street – which can be useful when using things like news and weather apps that need to know where you are in the world, but not to a few meters.
Go to Settings> Privacy> Location services and for each app you see a toggle switch for Exact location. If you just want to share your approximate location with that app, just add it Of.
Restrict Bluetooth data access
Bluetooth data can also be used to determine your location and should therefore be treated with caution. Some people prefer to disable Bluetooth completely, which can be done on Settings> Bluetooth, and this can be a completely affordable option for those who do not actually use the functionality. However, it is also possible to allow limited Bluetooth access only for select apps. To see these options, go to Settings> Privacy> Bluetooth to see a list of apps that have previously requested Bluetooth access. To give Bluetooth access to an app, switch the switch to On; to deny it, switch to Of. As with Location Services, let common sense be your guide. An app for a portable device that you control with your iPhone may really need Bluetooth access; a social media or photo editing app probably does not need it.
Use private Wi-Fi addresses
This feature is enabled by default on iOS 14, so there is not much to say here except that you should not disable it! When you join a new Wi-Fi network, your iOS device will identify itself to that network using a unique MAC (media access control) address. This helps anonymize your device when you connect to different Wi-Fi networks – since it connects to each of them with a different identification number, it will be more difficult for network observers to determine that two or more of these numbers actually belong to the same unit
Go to to see these settings Settings> Wi-Fi and tap the information icon next to any network. The Private address the option is turned on by default.
Disable tracking in Google Accounts
If you have a Google Account, there are some hidden location tracking settings that you should know about – and that you can disable at the account level, rather than just on one device. In iOS, from the Google app, go to Google Account> Personal & Privacy> My Activity. Here are two settings that affect how Google collects location data. One is quite clear: Position history. But the other is perhaps not so obvious: Web and app activity. This second setting controls another way that Google collects data on your device (including location data), even after pausing yours Position history. Turn off Position history and Web and app activity if you are concerned that Google is tracking your location. And at the risk of sounding biased, you may want to consider Apple alternatives to Google services, as these will generally handle users’ privacy better than Google.