Final answer:
It is against the law for individuals under the age of 21 to operate motor vehicles with any alcohol in their system, due to laws set forth by the National Minimum alcohal consumption Age Act of 1984 and reinforced by state zero-tolerance policies.
Step-by-step explanation:
For those under the age of 21, it is against the law to operate motor vehicles with any measurable amount of alcohol in their system. This is due to the National Minimum alcohal consumption Age Act of 1984, which mandated states to raise the legal alcohal consumption age to 21 or face a reduction in federal highway funds. Moreover, this law correlates to the operation of motor vehicles as states have implemented zero-tolerance laws, prohibiting underage alcohal consumption and driving.
Organizations like (MADD) played a significant role in lobbying for these legal changes as a measure to prevent such driving accidents. It's important to understand that the enforcement of these laws can vary by state, but the overarching intent is to discourage irresponsible alcohol consumption among youths and to increase road safety.