It's a little-known fact, but the ABA is just...a club, I guess, a guild, a professional association. Authority over lawyers and the practice of law rests with the Supreme Court of the United States, for federal law practice, and the highest Courts of the several States, for the practice of state and local law. In many cases, the courts look to the bar associations (there is one in each State, as well as many local associations) for "advice and consent," as it were, with their regulations but the court retains authority.