sjfcontrol wrote:Why couldn't the same thing be done with a vehicle that is done with a house?
The basic difference is that the car is moveable and the SCOTUS has looked at it differently. To stop a person from traveling (i.e. driving his car somewhere) constitutes a seizure and this also requires probable cause. If they have that much probable cause, the logic of the courts is to allow the search anyway to minimize the interruption time of the car owner when he is innocent and the PC turns out to be wrong. While the seizure of the house is also a seizure, it doesn't rise to the same level of interruption because they don't stop the person's movement. You can leave the scene if you want to and continue about your daily business. If you were just lounging at home, then this is less of an interruption, as the court sees it. A side note is that the court may see seizure of this type of a business as more of an interruption than a home, event though they generally allow more police latitude with businesses.
The 4th Amendment does not forbid searches without a warrant. It forbids unreasonable searches without a warrant. SCOTUS has ruled that this means a search is unreasonable without a warrant unless some other factors are present. The most common is exigent circumstances. While backing off slightly from the concept in recent rulings, SCOTUS had said in the past that a car was prima facie exigent circumstances because of the mobility of it. It was easy to get the evidence out of the jurisdiction or destroy it.
I have some questions on what the Border Patrol did, and the whole concept of the flexible border that allows for checkpoints away from the border itself. But from what I read of the original post, the BP acting in accordance with the current state of the law and court rulings as I understand them.
And, to answer one other question, the dog may have been trained only for marijuana or may have been trained to respond differently for different classes of drugs. This is much harder training, but it can be done. Some dogs alert by barking, some alert by scratching and digging, and some alert by sitting back and taking some position. It depends on the training and the dog's personality it displayed when it was being trained.