Final answer:
An open container violation occurs if there is any measurable amount of alcohol in a container within a vehicle, with laws varying by locality.
Step-by-step explanation:
An open container violation typically occurs when there is any measurable amount of alcohol in an open container within a vehicle.
The actual amount needed for a violation can vary by local and state laws, but generally, if there's enough alcohol that it could potentially be consumed, it might be considered an open container.
Note that laws can differ, so it's always best to check the specific regulations in your jurisdiction. For instance, in many places in the United States, a blood alcohol concentration (BAC) of 0.08% by volume is considered legally intoxicated for drivers, but this level isn't directly used for determining an open container violation.