The April 2002 ruling and the recent regulation states that a person who has an expired US visa cannot re-enter from Canada/Mexico if he is refused a visa there. But what if the person has an unexpired visa stamp on the passport and applied for a new visa in Canada/mexico and was refused? Suppose I go to Canada two weeks before my current visa stamp expiration and get refused, can I still come back on the unexpired visa? Would the consulate cancel the existing visa?