Digital Footprint: How Your Smartphone Can Be Used Against You

When I was 10 years old, my Aunt Naomi gave me a lined book for Christmas. It had no words in it, and I asked her what it was. She told me it was my diary and that I could write down thoughts there that were just for me. She also added that it was very bad manners for someone to read another person’s diary without his or her permission. Naturally, I wrote all manner of nonsense in that little book, including confessing to (some might say bragging about) small indiscretions.

One day, when I was supposed to be pulling weeds in the garden, I thought of a clever way to get out of it. If you simply buried the weeds with more dirt, no one would ever know they were there. It seemed like an elegant and time-saving solution to my problem of wanting to listen to the Cardinals play the Cubs in air-conditioned comfort. When I got inside, I wrote in my diary about how well that solution had worked.

My aunt was true to her word: She never read my diary. My cousin Jon, on the other hand, frequently snuck peeks and, on this occasion, ratted me out. He was mildly rebuked for reading my diary, but I was sent back outside to have another go at weeding the garden. From that day forward, I never kept another diary.

While the things you tell your priest, counselor or attorney are protected by privilege (at least in most states), what you write in your diary has no such protection. Diary entries are voluntary written statements not compelled by interrogation. A claim that the police exercised bad manners by photocopying your diary would not prevent a court from allowing the prosecutor to read every relevant page. If you ever had to defend yourself with your firearm, you would not want investigators reading a personal diary in which you had expressed every petty frustration.

Very few people keep diaries anymore, but every day, you carry a device that records your locations, conversations, thoughts and fears. That device is your cellphone. It’s more than a phone; it’s a pocket computer, and it never forgets.

As a concealed carrier, you must understand that what your smartphone keeps track of is not just about privacy; it’s about legal self-protection. In the aftermath of a defensive shooting, your cellphone may be the most important witness. It has no animus against you. It simply and dispassionately records everywhere you go. It could confirm your story, or it could raise questions you never expected to face.

What Your Phone Reveals About Your Location

A modern smartphone uses a combination of GPS, Wi-Fi, Bluetooth and cellular triangulation to track your movements, even when you aren’t actively using your device. Your phone likely maintains detailed logs of this data through a service such as Google Location History or Apple Significant Locations, and these logs are often stored for years unless you delete them regularly.

Why would your location data be relevant? In a criminal investigation, this information can be obtained with a search warrant consistent with the Fourth Amendment and used to establish or refute your presence at the scene of an alleged crime.

In a self-defense case, it likely won’t be an issue. You’ll call 911 before your barrel even cools, and the police will respond. But here’s how it could be used: Your location data shows your weekly trips to the gun range. It also records your visits to the sporting-goods store to pick up training ammunition. This is corroborated by the American Express app, which keeps detailed records of all of your ammunition purchases. An overzealous prosecutor might decide you were just “itching to kill somebody.” Jurors are not swayed by facts; they’re swayed by a narrative.

What Your Phone Reveals About Your Searches

Your smartphone probably either contains the Google app or uses a browser that connects to Google for searches. Your search-engine queries — whether through a browser, voice assistant or app — are logged and often synced to a cloud account. This means that if your iPhone has only 128 gigabytes of storage, your full search history may be stored in iCloud. While searching for terms such as “stand your ground” and “duty to retreat” is perfectly normal for a responsible gun owner researching the law, doing so shortly before a confrontation could be mischaracterized as evidence of intent.

A recent example of how location data and search history are used by law enforcement and prosecution teams is the investigation into the murder-suicide of a Utah family. An iPhone was found near the perpetrator’s body in the home where he murdered his family and then took his own life. His search history revealed that he had searched:
• “How loud is a 9mm?”
• “How loud is a 40mm [likely a .40 caliber]?”
• “Can you hear a gunshot in a house?”
• “Can neighbors hear gunshots?”

It constantly amazes me that criminals conduct searches like this on their phones or computers, seemingly oblivious to the fact that such data will almost certainly be recovered by police.

What Your Phone Reveals About Your Messages

Private messages, texts, DMs and emails are routinely recoverable (yes, even the deleted ones) through a forensic tool such as Cellebrite. In a self-defense case, these may:

• Help your defense (e.g., “Do we know anyone with a Jeep Cherokee? I’m afraid this guy is following me.”).
• Harm your credibility (e.g., “You know what I always say: ‘Shoot them outside and drag them inside!’”).

Social media posts, location check-ins and tagged photos can also be subpoenaed under the Stored Communications Act, 18 U.S. Code Section 2703. That means your entire Facebook, Instagram, YouTube and X histories may be made available to law enforcement.

And if your Apple Watch or Fitbit is synced to your smartphone, your biological data is also available. For example, if your heart rate spiked to 140 beats per minute at the moment of a self-defense incident, that could support your claim that you were in fear for your life. Conversely, if your heart rate never wavered and stayed at a cool 62 beats per minute throughout the exchange, it could be interpreted very differently.

What Your Phone Reveals in Court

Cellphones are central to modern criminal prosecutions. The U.S. Supreme Court acknowledged the unprecedented role of smartphones in Riley v. California (2014), holding that cellphones may not be searched without a warrant incident to arrest because of the vast personal data they contain.

But make no mistake: When someone is shot and killed, a search warrant won’t be far behind.

With a proper warrant, everything from GPS logs to deleted messages can and will be accessed to retrace your steps and question your motives. And those photos on your phone of you at the range, smiling in front of targets riddled with bullet holes? Those are coming into evidence too.

In the 2024 murder of Georgia nursing student Laken Riley, authorities relied on the victim’s cellphone to establish key elements of the crime. They obtained her iPhone’s emergency SOS data, smartwatch heart-rate readings and location history from the moment she left to go jogging. They used this data to reconstruct the moment of her attack and to place the suspect at the scene of the crime. In addition, the smartwatch itself became evidence when investigators discovered her killer’s thumbprint on it.

And even if you don’t have your cellphone with you on the day of a self-defense incident, your attacker may end up supplying the data through his or her own phone if he or she becomes a suspect and that information is subpoenaed.

What This Means for You as a Concealed Carrier

As a legally armed citizen, you have trained to put shots on target. You have worked to maintain excellent situational awareness, and your first-aid skills are top-notch. Your sidearm is well-maintained. You understand the gravity of carrying a firearm and, more importantly, the stress that may follow if you use it. Yet have you prepared for your phone to testify for — or even against — you?

Because your smartphone contains a wealth of data, it can either confirm your innocence or cast doubt on your motives. Location data may show that you drove to the gas-station parking lot to fill up your car just moments before you had to defend your life. But your search history might just as easily make you look guilty if it reveals that you had recently searched, “How many shots are legally allowed?”

Even if you’ve done nothing wrong, a prosecutor could argue that your digital footprint implies intent, aggression or reckless disregard for human life. And the fact that you were the victim of a criminal attack may never fit into the prosecutor’s narrative. To counter that narrative-building, you must take certain steps to ensure that your phone becomes your witness rather than the state’s witness.

What You Can Do Now

The first step is to review your phone’s settings. Every phone gives you the ability not only to manage your data but also to improve your privacy:

• Turn off or manage Location History in Google and Apple accounts.
• Limit app permissions (especially access to the camera, microphone and GPS).
• Regularly clear your browser history, and avoid syncing with cloud servers if privacy is a concern.

None of the precautions above will do you much good if you don’t exercise good message discipline. There are countless memes poking fun at dumb criminals, but remember that the people reviewing your Facebook, X and Instagram posts are unlikely to be sympathetic toward a firearms owner. If you give them ammunition, they may assume you’re no better than the criminal who tried to rob you. Therefore, abide by these guidelines:

• Avoid flippant or aggressive posts or messages about firearms.
• Don’t joke about violence or “getting even.”
• Don’t research legal doctrines on your cellphone.
• Assume anything you post or search could be shown to a jury.

Act Now to Stay Safe

Like it or not, your phone is your diary — one that tracks your every step, every search and every word. Unlike a physical diary, it updates itself. Unlike a locked journal, it can be seized, searched and used against you in court. And even if you delete that ugly text message you sent, it can likely be recovered.

But this doesn’t mean you should live in fear of your phone. Like your firearm, it’s a powerful tool. Used wisely, it can back up your story, corroborate your innocence and support your lawful use of force.

You’ve trained in marksmanship. Now it’s time to start training to manage your digital footprint.