[lmkg]

> Non-testimonial acts, like forcing someone to unlock a box, are not covered.

(IANAL) The example is not 100% applicable. You can only be legally compelled to open a lockbox if doing so provides no testimonial information. If there is uncertainty around whether you had control over the contents of the lockbox, then opening it would definitely provide that information. This action is therefore considered to have a testimonial component, and covered by the 5th Amendment.

You can still be compelled to open the lockbox, if doing so will not run afoul of the 5th Amendment. There are generally two ways to do so. One is that the action does not have a (non-trivial) testimonial component: If there is no doubt that you had control over the contents of the lockbox, then there is effectively no information being provided. The second way is that the testimonial component is not used against you: the prosecution cannot say that you opened it, but is otherwise allowed to use the contents as evidence (with caveats).