Since the NMDA, states have introduced a variety of additional laws to curb underage drinking, typically aimed at reducing access or availability, or setting consequences for alcohol use. All states currently have “zero tolerance” laws for alcohol consumption, which set the blood alcohol content (BAC) cut-off for minor drivers at or below 0.02 (the legal limit for adults, in all states, is 0.08). Evidence to support these laws is mixed. While some studies have found that zero tolerance laws are associated with decreased underage drinking others have found an association only for some subgroups of youth or no association at all
All states prohibit adults from furnishing alcohol to minors, although states often have exceptions to these laws, such as allowing a parent to serve his or her minor child in their own home. Many states have introduced additional laws to prevent retailers, parents, and other adults from supplying alcohol to minors. For example, many states have introduced “social host” laws, which hold individuals liable for underage drinking and/or the actions resulting from underage drinking that takes place on property they control. Other laws include a minimum age for people who serve or sell alcohol, and beer keg registration requirements, which enable tracking of retailers that sell kegs to, or adults who purchase kegs for, underage youth. However, these policies are not as well-studied and have less evidence of effectiveness