Why "it depends" is the honest answer
Three variables decide most phone-unlock situations: where you are (countries differ, and border zones differ from city streets), who is asking (a border agent, a police officer with or without a warrant, an employer, a court), and how the phone unlocks (something you know versus something you are). Change any one of them and the answer can flip.
Passcode vs Face ID: why the difference matters
Legal systems with a right against self-incrimination often distinguish between testimonial acts and physical ones. Revealing a passcode means stating the contents of your mind — courts in several countries have treated that as testimony that cannot always be compelled. Pressing a finger to a sensor or looking at a camera, by contrast, has repeatedly been treated like giving a fingerprint: physical evidence, more easily compelled. The case law is genuinely mixed and still developing, but the pattern explains a common piece of practical advice: in a high-stakes moment, a phone that requires a passcode asks more of the law than a phone that opens with your face.
Borders: the exception zone
Many countries treat their borders as places where ordinary search protections are reduced. Devices can often be inspected without the suspicion a street stop would require; refusing can mean a detained device, a missed flight, or — for visitors — refused entry. This is why travel advice from press-freedom and digital-rights organisations converges on the same theme: cross with less. Carry what you need, keep it minimal, and don't rely on the border being the place where your rights are strongest.
Compelled decryption laws
Some jurisdictions go further than searches: they have statutory powers to demand decryption keys or passwords in defined circumstances, with criminal penalties for refusal. Where such powers exist, the request arrives with legal force — the question stops being "can they ask?" and becomes "what happens when I answer?".
Where deniable encryption fits
Everything above concerns whether you can be made to unlock. Deniable storage addresses a different layer: what unlocking reveals. With a deniable vault design like Sealby's, complying is no longer all-or-nothing — you can unlock the phone, open a real vault, and cooperate fully, while the existence of any other vault remains unprovable. There is no list of vaults, no count, and unrevealed vaults are indistinguishable from random data. A demand can only target what can be shown to exist.
That is a practical property, not a legal loophole — it simply means the decision about what to disclose stays yours, even under pressure.
This article is general education, not legal advice. Laws on compelled unlocking and decryption vary significantly between countries and change through new legislation and court decisions. If this affects you, consult a lawyer familiar with your jurisdiction.