Short answer is yes, the police can run a drug dog around your car with limited exceptions. They can run the dog even when there is no evidence that there are actually drugs in the car. The reasoning behind this is that the Constitutional Right against unreasonable searches and seizures does not typically apply to situations where there is no reasonable expectation of privacy. The law states that if the drug dog is in a location where there is no expectation of privacy, in other words, a public place, then the drug dog is allowed to be there and can perform a sniff for drugs. The area around your car, so long as it is in a public area, is not considered private, so the dog can sniff around your car.
At the same time, courts have upheld that drug dogs have a special ability to smell drugs sufficient to provide probable cause. Probable cause is typically the legal standard required to get a warrant. In cases involving a vehicle there is an exception that says the police do not need a warrant to search the vehicle so long as there is probable cause that there are illegal drugs in the vehicle. This is essentially because vehicles are mobile and the evidence of the crime can essentially drive away. Therefore, if the drug dog sniffs out drugs inside your vehicle, it gives the police probable cause to then search your vehicle without a warrant. Most likely any drugs or illegal substances the police find as part of that search will be allowed as evidence in court against you.
Every circumstance is different, but typically the police need to be in a legal position when the drug dog actually sniffs out the drugs. Circumstances in Idaho that can be problematic is when law enforcement holds a suspect for longer than the original purpose of the stop. If the suspect is held for longer than the purpose of the stop, the police may not be considered in a legal position at that point, and a drug dog sniff may be held as unconstitutional. For example, if the police stop someone for speeding and there is no other evidence indicating drugs or other contraband in the vehicle, and the police call a drug dog and take too long to get there; longer than a typical speeding ticket would take, then the drug sniff could be bad and anything found as a result of the drug dog sniff could be suppressed (not admissible) as evidence.
These cases can be very complex and are very fact dependent, meaning that not all cases are the same. The specific situation of each drug case matters. Because of the seriousness of drug charges, it is important that you contact a Boise Criminal Defense Lawyer to help you in your drug case. An experienced Boise Criminal Defense lawyer will be able to recognize situations where searches for drugs by the police are unconstitutional, which could make all the difference in your case as it could lead to dismissal of your charges.