"authoritative interpretations of law FOR THE EXECUTIVE BRANCH." Suppose the National Security Agency comes up with a new tactic or operation and they want to know if it's legal. My guess is that previous to this EO, worker bees helped the NSA general counsel make a decision brief for the head of the NSA who then made the final legal/illegal decision. This memo means the AG or POTUS are now the decision makers. That's my reading of the memo anyway.