There's quite a lot about this that I like, but I think we need a way to handle investigations. Let's say I think I'm innocent and that a blood test might prove

There's quite a lot about this that I like, but I think we need a way to handle investigations. Let's say I think I'm innocent and that a blood test might prove it. Who decides whether I can order one done? What if the government decides that it's not a valid expense? Similarly, can I have expert testimony at my trial? Can everybody?