“Whose decision is it to put someone in jail if you fail a drug test while on probation?”
Well, if you fail a U/A while on probation, your probation officer will file a motion to revoke which causes paperwork asking that a warrant issues to be sent to the court for the judge’s signature.
On some minor violations the court will actually issue a summons instead of a warrant (at least in Austin) but most judges around here will authorize the warrant for a positive specimen.
So initially the ‘decision’ is the PO’s and the judge’s, if you’re talking about the decision to issue a warrant. If and when you bond out of jail, however you still face revocation proceedings in court.
I think this is what the question is really asking about, and the answer is: the judge.
In Texas – and I’d bet in almost every place as well – you are not entitled to a jury trial to decide whether or not you are in violation of probation. And worse still, the state need not prove the violation beyond a reasonable doubt, but only “by a preponderance” which means more likely than not.
So, try not to fail any U/As on probation, and there’s really only one good way to make sure of that, if you catch my drift…