In Illinois v. Caballes, the Supreme Court ruled that:

In Illinois v. Caballes, the Supreme Court ruled that:
 
  a. Drivers of automobiles have a reasonable expectation of privacy that protects them from the use of drugsniffing dogs without a warrant.
  b. Drug-sniffing dogs can only be used if there is reasonable suspicion the driver has narcotics.
  c. Drug-sniffing dog searches are prone to many errors and are so intimidating that officials must haveprobable cause to use them.
 d. The use of well-trained drug-sniffing dogs to expose contraband items that would remain hidden in a routinetraffic stop, does not intrude on a driver's reasonable expectation of privacy and the Fourth Amendmentdoes not apply.