The analogy that's sometimes used is that of a safe full of documents. Current case law says that you can be compelled to turn over a key but cannot be compelled to turn over a password [1].

The Department of Justice is saying that a fingerprint is more like a key than a password I guess. Or alternatively that unlocking phones is search and not testimony.

The EFF seems to be primarily objecting on the grounds that a search of "all devices in the building" is too vague to be a correct warrant.

[1] http://www.uclalawreview.org/the-fifth-amendment-encryption-...

Couldn't you say the same about a safe on the premises being searched?

The self-incrimination clause of the fifth amendment is broadly interpreted as intended to dissuade the government from attempting to coerce confessions. Forcing someone to unlock their phone with a fingerprint caries none of the moral hazard of forcing them to testify.

All of that being said, I'd love for US society to recognize that a search encompassing a bunch of people's phones is vastly more intrusive (by virtue of the volume of data collected and network effects) than a search of a building that excludes computing devices, and for us to require a correspondingly higher burden of proof.

How about we stop expecting "justice" to work in our favour and start forcing it to work in our favour?

If you don't want anybody to be able to take your stuff, don't make it possible for somebody to take your stuff. A piece of paper saying something isn't permitted is not going to stop it happening.

If the piece of paper says I can be forced to tell them my password, they will try to force me... and I will give my password. You can simply put people in jail for not disclosing their password, when the law provides these means.