The best way to protect your phone from a warrantless search in 2026

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ZDNET’s key takeaways

• US authorities are getting more aggressive about detentions and seizures.
• No single law governs phone inspections.
• Devices configured for biometric unlocking remain highly vulnerable.

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What’s the best way to protect yourself from authorities who appear determined to conduct unwarranted smartphone searches? When we explored this question a year ago, legal experts agreed that our legal rights in this area were murky at best, and ZDNET’s recommendation regarding device security leaned toward passcodes rather than biometrics.

One year later, does that advice still hold? The short version is yes, but it’s still complicated. Here’s what’s changed and what hasn’t.

Relying on biometrics was already risky

Last year, our legal rights regarding phone searches were uncertain. On the one hand, if your phone was locked with a passcode, any verbalization of your passcode can be construed as possible self-incrimination and a violation of your right to remain silent in the event of detention or arrest. Meanwhile, a biometric, such as a fingerprint, was considered “non-testimonial.” Given the relative newness of biometrics, it was unclear whether the laws that applied to a passcode also applied to your fingerprint or face ID.

When it comes to any form of enforcement, such uncertainty rarely works in a detainee’s favor.

“Biometrics are a more unsettled area of the law because [relatively speaking], devices are just starting to use biometrics,” said Ignacio Alvarez. A former law enforcement executive with the Miami-Dade Sheriff’s Office, Alvarez is currently a managing partner at the Miami-based ALGO law firm, specializing in civil and criminal litigation.

Also:7 ways to lock down your phone before heading to a protest

“The majority of the courts have found that being required by law enforcement to give your code to your devices violates your Fifth Amendment right against self-incrimination,” Alvarez told ZDNET last year. But he added that “the US Court of Appeals for the 9th Circuit just decided in 2024 that the Fifth Amendment protection against self-incrimination does not prohibit police officers from forcing a suspect to unlock a phone with a thumbprint scan. States courts have gone both ways on this issue, some claiming you cannot be compelled to use biometrics, but the US Supreme Court just denied certiorari on this case, so it will remain unsettled for now.”

For those reasons, ZDNET recommended that readers consider using a passcode rather than a biometric to unlock their phones.

At a minimum, your smartphone should be configured to require a passcode before its first unlock after powering up. However, for this to suffice as protection against an unwarranted search — at least one that doesn’t involve more invasive techniques or tools — you must have the presence of mind to power down your phone prior to the possibility of confiscation.

Biometrics are still risky

Nearly one year later, any conversation about your legal rights regarding the protection of your phone’s content seems almost trivial compared to the emergence of a domestic police state that disappears US citizens for days while seemingly testing constitutional boundaries instead of protecting them.

Earlier this month, NPR reported that ICE officers are taking DNA samples from protesters they’ve arrested, regardless of whether those people legitimately faced any charges or not. The article provides one account of a protester who was tackled and detained after allegedly doing nothing more than standing on the side of the road to film the actions of ICE officers. He was eventually released without being charged, but not before his inner cheek was swabbed for a DNA sample.

While that bigger reality can feel overwhelming, it remains important to keep tabs on the details, such as the ever-evolving legal landscape for your smartphone.

“In US v. Payne (2024), the Ninth Circuit held the government could require a suspect to use a thumbprint to unlock a phone without violating the Fifth Amendment,” said Joseph Rosenbaum, a New York-based attorney specializing in cybersecurity, privacy, and data protection at Rimon Law. Rosenbaum is one of the attorneys who was interviewed for last year’s story.

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We checked in with him again for this update. “But [after you interviewed me],” Rosenbaum told us, “the US Court of Appeals for the DC Circuit held [in US v. Jeffrey Brown] exactly the opposite, reasoning that requiring a suspect to demonstrate which biometric unlocked the phone is tantamount to communicating the individual’s knowledge of control or ownership, accessing potentially incriminating contents and [subsequently] suppressed the evidence presented by law enforcement.”

No single law of the land

Things appear no better at the state level. “In Florida alone, things are in flux,” said Alvarez of his home state. “One appellate district says it’s allowed, while three others say no.” Alvarez pointed out how every situation is highly jurisdiction-dependent. For example, if you’re arrested or detained by a police officer in one jurisdiction in Florida, the outcome could be very different from a detention or arrest by a federal officer in California (part of the Ninth Circuit’s territory).

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Technically, your rights with respect to your smartphone are very different at a point of entry into the US versus when you’re already within its borders.

In a New York Times article about what to do with your phone when entering the US, Tom McBrien, a lawyer with the Electronic Privacy Information Center (EPIC), is quoted as saying that “courts have generally seen [the search of a cellphone] as equivalent to going through luggage and have allowed manual searches to proceed without obtaining a warrant.”

A ‘growing surveillance arsenal’

Unfortunately, whether at a border or within the borders, seizures of smartphones, even if only for a short while, are raising new legal concerns about what happens to the device while it’s under an agency’s control. Or even when it’s not.

Last month, PBS News published an interview about the surveillance tools and tactics that federal immigration enforcement agencies are using. According to the story, immigration officials have a “growing surveillance arsenal” of tools at their disposal, including those from Paragon that allow “ICE or any government customer to remotely break into most likely fully up-to-date mobile phones.”

Also:How to delete or hide yourself from the internet – 11 effective ways

A similar post from the Electronic Frontier Foundation discusses other tools that the US government is procuring.

“One common surveillance tactic of immigration officials is to get physical access to a person’s phone, either while the person is detained at a border crossing, or while they are under arrest,” notes the article. “ICE renewed an $11 million contract with a company called Cellebrite, which helps ICE unlock phones and then can take a complete image of all the data on the phone, including apps, location history, photos, notes, call records, text messages, and even Signal and WhatsApp messages.”

When it comes to the current state of the laws in the US regarding phone seizure and search, EPIC Equal Justice Works Fellow Kabbas Azhar paints a troubling picture. His views aligned closely with those of Alvarez and Rosenbaum.

“The law is nuanced,” Azhar told ZDNET, alluding to the different laws across different jurisdictions and previous court rulings. Other than the DC Circuit’s ruling in US v. Brown that conflicted with the prior Ninth Circuit’s ruling in US v. Payne, Azhar said: “There have been no significant updates.” For example, the Supreme Court has yet to consider a ruling that sets the standard for the entire country, especially at ports of entry where immigration officers are taking action while detainees are technically outside of the US border (where entirely different laws apply).

But in terms of breaking into a phone black-ops style, Azhar said. “These are all things that we’re fighting against because they can’t possibly be constitutional. They [the US] say it is, which means it either has to be litigated or Congress has to pass a law.”

Even if new laws or court precedents emerge, Azhar makes a good point given the government’s tendency to stretch the law, if not break it altogether. While in one breath he discussed the need for the courts or Congress to step in, in the other, he said, “whether ICE or other federal agencies care [about the law] is a different question.”

Also: How passkeys work: The complete guide to your inevitable passwordless future

There’s already a 2014 Supreme Court decision (Riley v. California) on the books that essentially found it unconstitutional under the Fourth Amendment to conduct a warrantless search and seizure of a cellphone. But there are also some technical exceptions that the government uses to get around that precedent law.

What’s the bottom line?

Compared to this time last year, the only thing that’s certain is that there’s still a lot of uncertainty. And for that reason, it’s best to avoid a situation in which the only thing standing between the contents of your devices and a law enforcement official is a biometric. When and if that changes, we’ll let you know here on ZDNET.