This depends on where you are driving your car. There are some US States where you are legally required to restrain a dog when they are in a motor vehicle. These States include New Jersey, Connecticut, New Hampshire, Massachusetts, Maine, Rhode Island, Minnesota and Hawaii. However, new laws are being introduced all the time so it is always wise to keep checking the laws for the area where you will be driving. Even in areas that do not actually specify that dogs have to be restrained, there may be laws about preventing distractions when driving. If your dog is roaming around your car or even climbing on your lap, you could be convicted of distracted driving.