Is a company that makes safes legally required to have a master key or to create a master key even when they don't want to? The question is whether or not a 3rd party can be compelled to create something which does not exist in order to aid in the execution of a search warrant. I think it's pretty clear based on prior All Writs Act precedent[1] that Apple should not be required to produce new software code for cases like this.

[1] https://en.wikipedia.org/wiki/United_States_v._New_York_Tele...

I think there's a strong case for first-amendment rights in code signing even in the case of a non-ephemeral signing key. In any case, look at the use of a search warrant with Lavabit—is it clear that the All Writs act was even their strongest legal suit?