If Harry had been stopped at a sobriety checkpoint, the outcome of his case would be dramatically different. The Supreme Court has determined that sobriety checkpoints are legal, as long as they are conducted in a neutral manner. Stopping all approaching cars meets the neutrality requirement. Moreover, the Supreme Court has also determined that the use of drug dogs does not violate one's Fourth Amendment rights; commentators have called this the "plain smell" exception. A positive sign from a drug dog is sufficient to form probable cause that there are drugs in a vehicle, which then gives an officer the right to conduct a full search of the car...

Therefore, the prospects for success in Harry's possession case for the marijuana in the vehicle would change, because Harry would likely be found guilty. However, the nature of the stop would not have an impact on the legality of Hardbutt's interrogation of Harry; Harry still would have been entitled to Miranda warnings and any questioning without such a warning would have resulted in inadmissible evidence. The location of Harry's marijuana field would still have been fruit of the poisonous tree, and any drugs found on the property would still be inadmissible against Harry.