NOT so -- in the case of getting a warrant or court order. The authorities have to PROVE that just cause exists to a judge. In your case (which I'm sure happens a lot more than we realize), the officer "bluffed" just cause which may or may not have held up in court after the fact if the stop had been challenged. To get a warrant or court order - they start off in court proving their case

The courts. Just like getting a warrant for anything else. The authorities would have to prove "just cause" to obtain a warrant. If your spouse, child or parent were being held hostage and the authorities got the phone of one of the abductors, and it was hoped that information in the phone might help lead to their recovery, wouldn't it be worth it?