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Comment by gst | Hacker News Reader

If you do this on purpose after asked to unlock your phone you will probably be charged with destruction of evidence or something like that.

However, while a court is (afaik) able to ask you to put your finger on the fingerprint reader, you do not need to tell them which of the fingers the correct one is. So instead of purposely using a wrong finger, I'd ask the court to explicitly tell me which of my fingers I should use to unlock the phone.

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I think the court would similarly consider that obstruction and contempt. If they tell you to unlock your phone and you try to play some "first you have to guess which finger's the right one!" game, the judge will slap you with either contempt of court or refusal to comply with a subpoena.

IANAL, but I don't think there's much of a difference between asking someone to reveal the correct password and asking someone to reveal the correct finger. In both cases you would be asked to incriminate yourself.

If it would be lawful for a court to ask you to "unlock the phone with the correct finger" then they might as well also ask you to "unlock this harddisk with the correct keyboard keys pushed in the correct order (as a password)".

I don't think there's much of a difference between asking someone to reveal the correct password and asking someone to reveal the correct finger.

There's a huge difference. Authorities can force you to give up your fingerprint, but not your password[1].

1. http://jolt.law.harvard.edu/digest/telecommunications/court-...

It's the "which finger" that becomes similar to a password, not the fingerprint (ianal)

All the court cares about is for the person to supply the one that unlocks the phone, they're not going to play guessing games.

Courts care about precise distinctions of law (that's their purpose!). Seems clear that fingerprints aren't protected, basically the same thing as your face in terms of privacy given a good enough camera.

But they would effectively be asking you the question "which finger did you use to lock this phone" to which you may plead the 5th.

It'll be contempt and possibly more if you don't unlock the device with your fingerprint.

It's not hard, the "precise distinction of law," is "unlock this with your finger, whichever one does it." I don't know what complicated back and forth you're imagining, but it's never occurred in any case that I've heard of.

they would effectively be asking you the question "which finger did you use to lock this phone" to which you may plead the 5th.

We already covered this in the link above: the 5th Amendment covers passcodes, not fingerprints.

But, as Schrodinger says, this is not about your fingerprint; it is about a bit of information you have that the government does not have: which of your finger(s) this device knows about.

"A bit of information you have that the government does not have" is a password.

I really don't understand this line of thinking. What is the scenario you imagine where the question of "which finger?" is relevant? I'll lay out the beginning:

- Police want to get into your phone for some reason - You refuse to help them based on 5th Amendment or admiralty law or whatever - They go to court for a order compelling you to operate the touch lock to open the phone - You receive the order - ?

Please lay out the "?" part, if you don't mind. I'm highly curious.

> We already covered this in the link above: the 5th Amendment covers passcodes, not fingerprints.

No, it is you who is not understanding schrodinger's assertion. The secret knowledge of which finger unlocks it is in itself a passcode and subject to 5th Amendment protection.

OK, whatever you say.

Imagine you were to take the example further, unlocking the device required a sequence of fingerprint reads, with a precise ordering. i.e. left-ring finger, right index finger, right little finger, etc... That sequence would be a passcode, just as a precise sequence of keypresses would be. The government can insist on all your fingerprints, but not (in this argument) the correct sequence of uses of those fingerprints to unlock it. If it's only a single finger this same argument could apply.

I wonder if we can then reduce this example to a 1-finger sequence. Could a court require you to turn over all of your fingerprints, but not identify the (1 character) sequence?

As other have noted, the distinction is between fingerprints (all of them) and the correct fingerprint (one of them).

If you would like to claim that there's no difference between the two, then you (and your hypothetical court) should have no problem with a user supplying copies of all their fingerprints when asked to unlock their phone.

That's obviously not what's being asked for, hence other people's distinctions.

As I said, the court doesn't care about the, "which finger?" question. If they tell you to unlock your phone with the fingerprint that unlocks it, you replying with "which finger?" isn't going to help you.

Of course "the finger," and "which finger," are different things, but that's irrelevant.

Yes, and when they do force you to give your fingerprints they don't ask you what finger you want them to print they tell you which finger and when to print.

You better hope they don't say the one that you designated to unlock your phone?

Use your middle finger to actually unlock and use your index finger to fail. Unless the phone retains the biometric data after erasing itself, it's deniable.

This might work in the short term, but if enough folks actually did it, there would soon be a law that you may only use your thumb to unlock your phone.

Why not just turn the phone off instead.

It would be a very long and involved case, anyway.

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