California Motor Vehicle Code 23112
No Throwing, Depositing, or Dumping Matter on a Highway
There are a variety of reasons why it is illegal to toss things on the highway. For one, it is considered littering and contributes to pollution. Secondly, if a driver throws something on the road, who does he or she expect will pick it up? Thirdly, it is a hazard and could cause a collision.
Vehicle code 23112 explains that no one - driver, passenger or pedestrian - shall throw or deposit anything on the highway. This includes but is not limited to: bottles, cans, garbage, nails, offal, paper, wire, or any offensive material of any kind. Even dirt and rocks can be a hazard if placed on the road without consent of the state or local agency.
If a driver drinks a cup of soda and tosses it out the window, it could hit another driver's windshield and make it very hard for him to see and continue driving safely. If someone deposits nails or sharp objects on the road, another driver could experience a blow out and lose control of his vehicle. If someone loses or places a piece of furniture in the road, it could cause a traffic jam as other vehicles have to slowly switch lanes to avoid the obstacle.
Drivers should secure items being transported so they are not lost during transit and become road debris.
It is the responsibility of all who use the road to be considerate and keep it clean.