I'm actually of a couple of minds about this... although the majority of my issues (as such) are me speaking with my lawyer hat on.
First, I'm fairly happy Obamacare remains because I like elements of Obamacare in principle. When discussions about healthcare systems come up I tend to mention my support for the Swiss approach (private insurance but each insurer must
provide a basic package which covers a selection of things and which they cannot
make a profit on, with the government giving subsidies to those who can't afford even the basic package); in the rough comparisons between different systems we have it gives the same or better results than most others at less cost. For all its flaws Obamacare does follow a similar set-up.
Secondly, this complaint was basically the definition of a technicality; it was an attempt to essentially decapitate the act because of one clause being poorly worded and some sloppy definitions. If Obamacare is to be repealed or replaced it shouldn't be on the basis of a technicality; it's too important for that.
With my legal hat on:
There's a school of judicial interpretation of statue
related to "mischief". This isn't a fancy term for judges causing trouble; it's an approach to interpretation where when a judge is called upon to interpret a statute he looks beyond merely the pure text and instead looks at what "mischief" the statute was intended to correct in the first place. An example from the UK relaters to sex work; a law was passed which made it illegal to "loiter or solicit in the street for the purposes of prostitution" but sex workers were calling down to men from balconies. When arrested they claimed that as they weren't "in the street" the law didn't apply to them. The judge looked at the discussion in parliament behind the statute, decided that the purpose of the act was to prevent the mischief of harassment from sex workers and basically quashed the loophole.
I have mixed feelings on the mischief act. On one hand it prevents those loophole issues mentioned above. On the other hand, is it really the job of the courts to correct the legislative's poorly drafted bills? Or on a wider sense to basically guess (however well informed) what they meant? As a general rule the way statue-based law works is that it's based on statues interpreted by the judiciary. But the mischief method isn't a judge interpreting the statute, it's them interpreting the intentions behind the statute. That's a different and far wider thing.
In this case the issue comes down to this: tax credits were available to anyone enrolled in an insurance plan "through an exchange established by the State". But 34 States don't have their own exchanges, instead having a federally established one. Does a federally established exchange count as being established by the State? The act itself would suggest not; in the definitions section "State" is defined as being "each of the 50 states and the district of Columbia" which doesn't include the federal government. Thus, looking purely at the technical wording of the act tax credits shouldn't
be available to the residents of states which only have a federal exchange.
The majority basically used the mischief method. The "mischief" the ACA set out to right was the poor access to and high costs of healthcare (it may or may not achieve those aims but that is the purpose). Strictly following the wording and thus preventing people in certain states from getting tax credits would have gone against that purpose and thus the wording is changed. But as Scalia points out (and agree with him or not, he writes clearly and entertainingly) it's a challenge to find a more plain limitation than "established by the State" (if it is established by the State it's allowed, if it's not it isn't) and State in turn is clearly defined. Using the mischief approach here is to say that those words no longer have any meaning. Moreover in other sections of the ACA there is a distinction drawn between "exchanges" in general (i.e both federal and state exchanges) and "exchanges established by the State". That being the case it seems clear that "exchanges set up by the State" is not
simply shorthand for "all exchanges, federal or state established". In addition the US tends to use a less wide version of the mischief method; only when the wording is ambiguous should the purpose of the act be considered. Here the wording isn't ambiguous, it's clear and it clearly excludes people in states with federally established exchanges from getting tax credits.
Frankly, I prefer Scalia's reasoning. Which I really dislike doing. Because as above I don't want the ACA repealed and, if it is to be repealed or fail, it shouldn't be on the basis of something like this. But his reasoning is clear, to the point and convincing. The majorities is fudged and trying to bend things as much as possible to suit their view.