Laws concerning leaving a dog unattended in a car vary from state to state. Only 14 states have statutes that forbid leaving pets in a confined vehicle, according to the Animal Legal and Historical Center's 2013 report. In general, conditions in the car must not endanger the animal's life.
Some laws specifically state that extreme temperatures and lack of ventilation meet this specification. Courts also consider whether the owner has failed to provide adequate food and drink for the pet. Campbell and Pima Animal Care in Arizona states that reckless endangerment of a dog can result in up to 6 months in jail and a $2,500 fine.