I'm not sure it matters. Whether Congress creates a new law overwriting the old, or passes one that tries to explain the old differently than it was executed on

I'm not sure it matters. Whether Congress creates a new law overwriting the old, or passes one that tries to explain the old differently than it was executed on, if anyone doesn't object it's moot, and if anyone does, it will end up in the courts. Particular to this case, Congress could do either, and either way the courts will have to decide whether it's fair to do. But, also particular to this case, Congress has done neither, so the courts were left with interpreting what Congress last decided.