Do you feel that the 4th amendment should protect them? Or perhaps a new amendment should be written to protect them and abolish power of subpoena?
I’m slightly biased as I ask this. I feel that the mind is “sacred” in a sense, that it should be considered a fundamental human right for an individual to be able to preserve privacy over their internally held thoughts and memories, and that the ability of the court to force an individual to speak or disclose part of their mind is a wild overreach of power and an affront to the personal liberty of the innocent.
The prosecution generally does not call recalcitrant witnesses because they make bad ones.
Corroborating evidence. If multiple people say “yeah Jimmy saw the entire thing”, that’s how you know. The lawyers can’t just say “we think @[email protected] was there so they have to testify.” Mostly because you’d make a terrible witness for the prosecution (or the defense).