Blood alcohol content for drivers is a state or local issue.  The federal government only establishes a blood alcohol level (unconstitutionally) by blackmailing the states through the federal highway fund:  if a state refuses to accept the federal mandate, no highway subsidy.
Then each state can establish its own standard for a blood alcohol level.

    Through experimentation with 50 states, and even more at the local level, a sensible standard can be set.  Right now it appears anything below .12 is just “feel good” politics as according to statistics the vast majority of alcohol related accidents occur at that level or above.

    A regulation lowering the level to .08 is the result of politicians looking for votes, not sensible legislation.