Erieblogging: Day Thirty

My penultimate Erie question is about the District of Columbia. I’m not concerned here with the puzzle of how Congress can send a state law cause of action between a citizen of a state and a citizen of the District to federal court, given it is not a controversy between “citizens of different states" under Article III. 

My question is about the fact that "federal" courts (including the District Court for the District of the District of Columbia, the D.C. Circuit and the Supreme Court) defer to the "state" supreme court, the D.C. Court of Appeals, concerning D.C. law, as if Erie applied here.  But that's nonsense: D.C. is a federal enclave and the "state" supreme court is itself a federal court. 

D.C. has its own common law (often borrowed from Maryland common law). This is a body of federal common law for the District, which, prior to 1970, was developed by federal courts. Why then aren’t federal courts still interpreters of D.C. common law? Furthermore, much D.C. statutory law consists of Acts of Congress, and even acts of the D.C. government are the exercise of delegated congressional authority. So why don’t federal courts have interpretive authority over D.C. statutory law?

The argument for deference is the District of Columbia Court Reform Act of 1970, which intended to make the D.C. Court of Appeals the equivalent of a state supreme court. I question whether Congress really could make the U.S. Supreme Court defer to another federal court concerning the content of federal law. But setting the Supreme Court aside, this isn’t really Erie were talking about here, right? This is some fake federal statutory equivalent of Erie. Shouldn't that matter?

(Parallel posted on Michael Green's Civ Pro Blog.)