You could show that they accessed a device or used a service immediately prior to being subject to litigation (through network logs for example). A judge would

You could show that they accessed a device or used a service immediately prior to being subject to litigation (through network logs for example). A judge would not believe the person didn't remember the password in this case. If they destroyed the keys after receiving a request for data then that would be destruction of evidence which is already punishable. If the data is held by a third party then the third party could perform a password reset.