You should not leave a child unattended in a motor vehicle for any length of time. If children are trapped inside cars—especially in hot weather—they can suffer from heat exhaustion or heat stroke in a matter of minutes, leading to permanent disability or death. Heat stroke, also known as hyperthermia, can cause shock, seizures, irregular heartbeat, and heart attack, as well as brain, liver, and kidney damage. Leaving a child unattended in a car is also a form of neglectful supervision that is investigated by Child Protective Services.

In Maine, leaving a child unattended in a motor vehicle is considered a serious matter, especially given the risks associated with heatstroke and other heat-related illnesses. While Maine does not have a specific statute that makes it illegal to leave a child unattended in a vehicle, such actions can fall under child endangerment laws. Maine statute Title 19-A, Section 4002 defines a 'child' as a person who has not attained 18 years of age. Under Title 17-A, Section 554, endangering the welfare of a child occurs when a person knowingly endangers the child's health or welfare by violating a duty of care or protection. This can include leaving a child in a situation where they could suffer from heat exhaustion or heat stroke. Additionally, such incidents are likely to be investigated by Child Protective Services as potential neglectful supervision, which can lead to intervention and possible legal consequences for the responsible adult.