That's in the fantasy world of constitution maximalists. In real world it doesn't work like that and you might still lose money/time/your sanity fighting a system who cares less and less about your rights
Do you think this is for fighting parking tickets? It is for journalists to not reveal their sources, whom might be at risk of severe consequences including death.
That's a whole lot more to loose than your money and time.
The case law on this specific topic is convincing. If you are ever in that situation it is usually going to be worth your time and money to assert the right and see it through. Case law supports this. The general maximum “penalty” is being held in contempt of court. And if the government is wrongly persecuting you, it is lose / lose if you divulge.