Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.
Eighth Circuit: United States v. Javier Pulido-Ayala
Instinctive jump into the car by police dog (aka: "Jampy") was constitutionally permissible search, as the dog's initial movement towards the car would have justified the search.