>withholding evidence from the prosecution, you are going to jail if you follow.
Prosecution must present a valid search warrant for *specific* information. They don't get a carte blanche, so uber way is correct. lock computers and lets the courts to decide.
In common law/4th amendment, kinda. Once you have a warrant, then the word reasonable comes into play. Its reasonable to assume that the data you want is on the devices of certain people. if incidental data/evidence is also procured that was reasonably likely to contain said data, then its fair game
In the civil code, its quite possibly different. The french have had ~ 3 constitutions in the last 80 years. The also dont have the concept of case history. who knows what the law actually is.