Why else would the Obamacare case, King v. Burwell ever get to the Supremes? The ACA clearly states that federal premium subsidies are available for insurance purchased through "an exchange established by the state."
Not very ambiguous, is it?
But his BO'ness and Herr Gruber, saviors of us stupid voters, tell the courts that the Congress intended those subsidies to also apply to federal gob'mint exchanges. In a thousand page law (years in the making), I reckon if that was the intent of the Congress, they had room to say so ---- and did not!!
So, I ask again - what is there to interpret? It's not written in Mandarin, nor Farci, nor Spanish.