Interesting fact: How evidence was obtained is only important in the US. For example, in Austria where I live, it doesn't matter how the evidence was obtained.

In Austria, if someone illegally spies on you, the information they collect can be freely used in court. It is not important where the evidence comes from, it is only important if the evidence is credible or not.

This doesn't mean that the police can do whatever they want; if they torture someone, a potential confession would be worthless because it wouldn't be credible. And if the police used illegal means, that would bring about a separate trial (in theory).

But courts in Austria never have to pretend that some evidence doesn't exist.