Since my post on Halbig and originalism drew several great comments (including a response by Larry Solum here), I thought would add some clarifying thoughts.
My point is that recovering the original public meaning of a legal text is often much harder than people care to admit. Historians are more likely than lawyers to say that the meaning of a past event is indeterminate. Now does this mean that we can never know the original public meaning of something? No. Does it mean that we should not try to know? No. Originalists, in my view, just tend to be overconfident in what they think they know or can figure out. If we are having a hard time with something from four years ago (assuming you believe that is the case), then where are we for texts from two hundred plus years ago?
Now the best rejoinder to the specific claim in my post is that a complex statute like the Affordable Care Act is not comparable to constitutional language. The latter gets more widely discussed and is easier to understand. That is true to some extent, but I’m not sure it’s a total winner. People are always surprised at how little Section One of the Fourteenth Amendment was discussed at the time, for example, and you can find examples of statutes that were discussed in far greater detail (the Civil Rights Act of 1964, for example).