If it can be credibly demonstrated that she cancelled the hearing and escorted the defendant out a back door within seconds of sending the officers away, that she had every intent of proceeding with the hearing before meeting with the officers, and that she and her peers did not usually use that door for defendants, then I would consider that to be proof beyond reasonable doubt that she intended to obstruct the arrest.

It's not a given, but it doesn't seem like an insurmountable burden of proof either.