Lots of the coments have attacked various notions of originalism and argued for the inevitable influence of a Justice's policy views on outcomes in at least close cases. A couple of observations.
First, I do think that a theory of originalism focused on the public meaning of speific words at the time they were used is indeed the correct (indeed, the sole correct) approach to interpreting written instruments, whether they be constitutions, statutes, or contracts. I think that conclusion flows inevitably from the bare fact that we have selected a written instrument to convey and enshrine our rights and obligations.
Second, while I think that a basic historical/textual analysis of the written instrument indeed resolves most of the questions that arise, I have already noted that such an approach does not resolve all close cases. Under those cases I have noted that we have canons (note the proper spelling this time -- I am educable, even if a naturally poor speller) of construction that provide an answer on how to resolve the ambiguity. (The cannons will have to be saved for those instances in which the canons do not adequately resolve an issue that is extremely contentious and cannot subsequently be resolved by the political branches.) I recognize that such canons do not have the inherent certainty or even "correctness" of textual rules, but at any given time they generally have the force of precedent and hence are correct within the particular legal/temporal context in which a given case is decided. Can those canons change over time to lead to different results in ambiguous cases? Of course, but even such changes are mediated by other structural rules such as stare decisis and hence one can ascertain whether a change in canons is "correct" based on the legitimacy of the process and reasoning through which the change is made.
Whatever the canon is at any given time, however, I would argue that its uniform application to all cases is the measure of a jurist's fidelity to the law and to the role of the courts. Whether we apply a liberty-favoring canon such as suggested by Prof. Barnett, or a deferential canon such as not overruling the political branches unless they violate some "clear" constituional command, we should apply them consistently regardless of whose ox is being gored. (I think that answers the commentator who asked whether the consequences of a decision influenced its correctness: The answer is no, the legal correctness of a decision is indeed independant of its effects. That is true of Plessy, Brown, and any other sacred cow one cares to raise on either the right or the left. I am not saying Plessy or Brown was right or wrong legally, just that the answer to the question has nothing to do with whether the results were universally acclaimed or condemned.) If we do not like the result, do not blame it on the jurists, blame it on the law and change the law, by constitutional amendment if need be. The complaint that amending the Constitution is difficult moves me very little. If the consequences of a bad decision are so overwhelming as to get everyone into a lather, you would think that would be sufficient to motivate folks to do the hard work of amending the Constitution. If the real problem is that the public is split on the right answer, though equally vehement on both sides, that strikes me as precisely the sort of situation in which an amendment would be inappropriate and we need to stick to the earlier rules until a sufficient consensus builds for a new rule.
Third, I am perfectly willing to acknowledge that a jurist's policy preferences might influence which canons of construction he or she chooses to endorse and hence to that extent it is relevant. But I think that most canons of construction tend to be very context-specific in terms of whether they will indeed promote or retard a particular policy bent, and hence the influence of policy preferences on canon selection is limited at best. A pro-liberty canon that curtails government power might be pro or anti "rights" depending on what a given piece of legislation says. Where the political branches are creating new rights such as in the civil rights context, such a cannon will work to the detriment of the folks being given new rights and to the benefit of folks being subject to new obligations. Where the law is restricting rights or expanding government intrusion into individual lives, the consequences will be the opposite. While a jurist might try to mak a list of how many prospective results would be favorable or disfavorable to his or her individual policy preferences, that exercise is fraught with uncertainty and not likely to give a policy-concerned jurist much to go on.
Again, my primary criteria is that the canon be applied consistently regardless of substantive area or result. If a jurist applies the canon only when the result is favorable and ignores it other times, then that jurist abandons the judicial role and is rightly subject to criticism. But I think Judge Roberts has made a strong case that he will be ever-vigilant in seeking equal application of the law, outcomes be damned. Folks may not believe him, but he seems credible to me, and I think his answers are a full and complete response to the attempts to probe his policy preferences. (I also disagree with commentators who say that Scalia and Thomas only use their judicial approaches as a mask for policy choice. There are plenty of good examples of them voting contrary to their presumed and sometimes expressed policy preferences. The notion that those are only in areas not important to them is palpably wrong, and I have not seen persuasive examples condemning their consistency in cases where their reults were presumably more to their liking.)
To the extent a jurist does not take the approach I endorse, but instead favors a living or evolving Constitution and the abstract search for new rights (or new powers for the government), then I agree that policy preferences are more likely to influence that jurist's results and hence an inquiry into those preferences is reasonable and likely necessary. And because so many Justices in modern times have taken that approach, Prof. Cross's statistical evidence of ideological bias is hardly surprising, but somewhat misses the point.
If you believe Judge Roberts regarding his jurisprudential approach, further questioning of his policy views is of little or no benefit. Saying that others in the past have used their policy preferences to skew their judicial results is hardly a basis for demanding that Judge Roberts, who professes a different judicial philosophy, answer questions better directed at those others. And I think such questions, by politicizing the role of a Justice and by effectively endorsing such a policy-driven approach, are very destructive. Indeed, it is the invitation to politicizing the decisions of the Court that stands as an indictment of the more open-ended jurisprudences of some justices and argues in favor of a more constrained jurisprudence such as I have described.
If you do not believe Judge Roberts regarding his judicial philosophy, then I suppose that is reason enough to vote against him. But I am not willing to impute such dishonesty to him, and I do not think it reasonable for others to do so.