I have not followed all the ins and outs of the debate on subsidies on federally-created exchanges. However, it appears that opponents of Obamacare, combing through the vast mountain of material on the law's enactment, have found two videos by one of the architects of the law seeming to suggest that he thinks only people who buy insurance on state-created exchanges will be eligible for subsidies. Against this is the vast quantity of evidence that they intended nothing of the kind. Which should carry more weight?
Let me digress for a moment to talk about my law school days and the fascinating Professor Fritz who taught history of law. He disagrees with people who look down on "law office history," i.e., the selective marshaling of historical evidence to make a legal point. To criticize law office history, he says, is to expect lawyers to act like historians rather than lawyers. He made this comment in the context of some Scalia opinion that justified itself with an extraordinarily dubious historical argument. He said that there is no point in criticizing Scalia for cherry picking and quoting out of context -- that is what lawyers do.
My answer to that is two-fold. First, I can attest that lawyers act as zealous advocates of their clients and do, indeed, cherry pick and cite out of context. They are allowed to do so because there is always a lawyer on the other side pointing out when they cherry pick and cite out of context so the judge will not be deceived. Judges, on the other hand, are not supposed to be advocates. When a lawyer presents a load of bullshit under the guise of advocacy, it is the judge's job to point out that it is bullshit and go with what the law actually says, no cherry picking or citing out of context. Sometimes the law is unclear and a judge must decide between two (or more) plausible interpretations. But it is a judge's job not to be bamboozled by a clever lawyer, not to be the clever lawyer doing the bamboozling. My other answer is that if lawyers (or judges) are not historians, then they shouldn't impersonate historians.
Suppose I decided that our current form of jury trial that requires a unanimous verdict of twelve jurors in a criminal case is too long and cumbersome, and that we should instead have thirteen-member juries that decide by simple majority. Sounds crazy, no? And to advocate such a thing now would be crazy. But I could make a decent law office history argument that this was the original intent of the Founding Fathers. First, I would point out that the original body of the Constitution, before even any amendments were added, says, "The Trial of all Crimes, except in cases of Impeachment, shall be by Jury." (U.S. Constitution, Article III, Section 2, paragraph 3). I would further point out that when debate on the U.S. Constitution began the very first opinion published criticized the requirement that a jury verdict be unanimous and called for a 13-man jury to decide by simple majority. And no one seems to have refuted this argument.
Of course, anyone opposing me will have ample counter-argument. This was one opinion expressed out of an approximately 50,000 pages that have been preserved from the time. The reason no one even attempted to refute it was that it was such an eccentric viewpoint as not to seem worth even debating. A huge volume of commentary exists praising the (unamended) Constitution for requiring a jury trial in criminal cases and demanding to know why it did not require a jury trial in civil cases as well. When various state conventions proposed amendments, the one thing they all agreed on was that trial by jury should be required in civil cases as well. In short my argument would be every bit as crazy as it sounds. But if a serious political movement got underway for 13-member juries to decide by majority vote, this argument would no doubt get a respectful hearing from the courts and whether judges accepted it or not would depend on whether they favored or opposed such juries, not whether the argument was good history. (It is not).
The same applies to the Obamacare debate. The lawyers who argue that really Congress intended only people buying insurance on state-created exchanges to be eligible for subsidies and wanted to deny them to people buying insurance on federal exchanges are practicing a bit of law office history, albeit of a very recent event. In this they are only acting as zealous advocates of their clients, and I don't begrudge them the argument. The other side should respond by practicing its own law office history and pointing out the vast mountain of evidence to the contrary. What does bother me is the thought that it is judge's political inclinations, not the actual evidence, that will make judges decide whether to accept this bit of law office history or not. Lawyers may acceptably practice law office history; judges may not.