you’re not understanding.
the information they gathered would never be used anywhere in proximity to the judicial system
BUT... it would be used to tip them off who they should monitor more closely through ‘legal’ channels... so they could get a warrant and bring charges.
in the rare circumstance they gathered something that was immediately actionable (someone was about to deliver a bomb or something)... they would just take out the target and claim terrorist threat. no evidence or warrant needed.
They don’t turn everybody’s microphone on. They are targeting troublemakers and they have not gotten a named warrant. You can count on it. The other ubiquitous recording of metadata (supposedly) doesn’t include the message body ( but it does - illegally). They are all liars.