Originalism rose to prominence in the Reagan era because, as Edwin Meese put it in an uncharacteristic moment of candor, it promised to remake the Court in a way that would halt the slide toward "the radical egalitarianism and expansive civil libertarianism of the Warren Court." Originalism was successful because it implicitly pledged to reconstitute the Court in ways that would entrench conservative values in matters of faith, family, race and property. Wherever the theory of originalism produces results that are inconsistent with this pledge, it is blithely ignored. Voters are not attracted to the discipline or jurisprudence of originalism; they are drawn instead to its capacity to reshape Supreme Court precedents into a "living constitution" for right-wing convictions.
This, to be clear, is true for how virtually everyone who doesn't have a J.D. (and a fair amount who do) comes into their legal position, regardless of what it is.
Nonetheless, some folk do at least purport to assign originalism some special interpretative value. Unfortunately, many of them seem to have but a weak grasp of what originalism actually entails. For one, they often blend "originalism" and "textualism", when the two are actually very different things and often radically opposed to each other. But in this post specifically, I'm going to try and deal with the fact that the unitary category "originalism" actually is splintered into at least three different interpretative approaches, ones that have some commonalities but have important differences as well. The three are "original intent", "original meaning", and "original understanding", and at the very least someone who claims to be an "originalist" needs to clarify which of the three schools they are an adherent to.
I. Original Intent
Original intent is probably what most lay people immediately think of when they hear "originalism", and I suspect it is the oldest of the three categories. However, my understanding is that it also has the fewest true adherents today. Original intent argues that a law, statute, or clause should be understood as doing what its drafters intended it to do. The 13th Amendment was meant to bar slavery, but its framers did not demonstrate any intention for it to bar segregation (as plaintiffs alleged in Plessy v. Ferguson). What could be difficult about that?
Well, lot's of things, actually. First of all, intention is often unclear: not every legislator announces why they are voting for a particular bill or amendment, and sometimes different legislators vote the same way on the same bill for radically different reasons. In this case, whose intention is controlling? Second, anyone who observes politics knows that a sizable portion of votes aren't cast based on "policy" grounds at all. Senator A may vote for a bill requiring hospitals to fund abortions for poor women because he genuinely believes that these women should have access to reproductive choice. Senator B may not agree with that, but he votes "aye" because he's worried about his re-election chances in his moderate, pro-choice district. Senators C and D don't care about the issue at all, but C just votes the party line and D wants to log-roll with A later. Sometimes, a whole bill can put up with the primary purpose and intent of simply embarrassing or harming the other party. The rejection of the Lofgren Amendment to the Unborn Victims of Violence Act indicates that this was a major function of that law. How does a Court interpret the "original intent" of a law when half or more of the legislators' intent had nothing to do with the policy at issue? Finally, occasionally a key legislator will vote for a law with intentions radically opposite those indicated by the text. Senator Howard Smith of Virginia, for example, inserted the clause in the 1964 Civil Rights Act that protects women as a "poison pill", he assumed that by adding it, he could pluck off enough Senators from the affirmative side to kill the bill. Needless to say, this didn't work, but it leaves us with the peculiar position of having a clause in the Civil Rights Act the "original intent" of which was to sabotage the bill.
For these reasons, most academic originalists have been abandoning "original intent" for one of the other two originalist approaches, which I'll outline below.
II. Original Meaning
Original meaning treats the terms in legal texts as terms of art -- that is, terms with specific and well-defined legal definitions that may not be obvious to a lay reader. For example, in 8th Amendment cases Justice Thomas has argued that, at the time of the framing, "unusual" did not simply refer to rare or uncommon punishments, as the term implies. Rather, it had a specific legal meaning from English Common Law. An "unusual" punishment was a punishment that was not previously spelled out in law: if execution methods on the books were hanging and the firing squad, a court couldn't sentence a convict to be drawn and quartered.
Original meaning is particularly useful, then, when a jurisdiction adopts a law or rule that has been in place in other locales for a long period of time, and thus has a surrounding body of precedents and history that can be drawn on to define the term. For example, several jurisdictions have passed Equal Rights Amendments. When, say, Maryland passed its version, it presumably "knew what it was getting into" because it had seen how other states had utilized their ERAs, and passed its own version with an eye to the meaning as expounded by other states. My reading of the Maryland Supreme Court's analysis of the Article 46 claim on the recent gay marriage decision is that the Court was engaging in original meaning jurisprudence as to the parameters of Maryland's Equal Rights Amendment (specifically, does the language as a term of art require discrimination to be "as a class"). Importantly, "original meaning" does not directly look to see how the action under question would have been treated at the time of the framing (in the gay marriage example, it's not concerned with whether gay marriage was considered to be protected by the ERA in 1975). Rather, it looks to understand the parameters of the legal principle at the time, but it can then apply the principle in whatever manner seems most apt.
Of course, many laws do not have such obvious analogues to the proceedings of foreign jurisdictions, and in these cases original meaning becomes fuzzier. OMers can attempt to look at the legislative history and political commentary surrounding the act, but this often significantly more inexact and fails to define terms as terms of art. In the Maryland case, for example, the majority conceded that the specific texts and history it could bring to bear on the issue were very scant, and it wove a few scattered newspaper accounts and some US Senate testimony, mixed with more contemporary precedent, to reach its decision.
III. Original Understanding
Finally, original understanding asks how a particular law, policy, or action would have been understood by the population at large to apply at the time of enactment. Would the population have understood the first amendment to protect obscenity in 1795? Would American's have seen school segregation as unconstitutional in the immediate aftermath of the 14th amendment (would they have thought that a proto-affirmative action program had to be barred?). In contrast to original meaning then, original understanding looks at the policy in question, rather than the legal principle surrounding it.
Original understanding probably gets closest to the prime virtue of the originalism movement, which is avoiding "nobody saw this coming" moments. But on the other hand, it can lead to results wildly at odds with the text it purportedly emanates from. The Alien & Sedition Act, for example, passed very soon after the ratification of the 1st Amendment, prohibits conduct that is unquestionably "speech" and well within the confines of the Amendment's protection. Original understanding also runs into problems in that it assumes the populace had a well-defined idea about how the clause would apply in every case -- and many cases are unexpected. I suspect that most cases that arise under most amendments deal with issues that most people didn't have an opinion pro or con on at the time of ratification. And finally, because it tends to look at the policy, rather than the legal text and principles themselves, it seems to stray the furthest from "classic" legal decision-making, which is supposed to abstract itself from the particular policy in question and instead apply generally applicable legal principles to resolve interpretative issues.
I've tried to sketch out the boundaries of the three major originalism schools, as I understand them, and how they differ from each other. Each of them has its own advantages, and, naturally, its own weaknesses, both of which I've laid out (in very abbreviated form). It goes without saying that I believe there are inherent weaknesses within the originalism project as a whole that affect all three schools: from the "there's no original evidence for originalism" gotcha, to the fact that people are fragmentary and don't understand the same texts in the same way (which is why we argue about these things in the first place), to the point that at least some portions of the constitution appear to be written precisely to be temporally variable (e.g., what's "necessary and proper" to carry out legislative functions, Art. I, Sec. 8 at one point in time may not be in another). And, to reiterate the point I made above and in my Madison's Tomb story, very few conservative adherents of originalism would continue to do so if originalism wasn't seen as legitimizing their preferred political ends.