The Empirical Legal Studies blog is running a series of posts about what is called "The New Legal Realism Project," which is centered at the University of Wisconsin, Madison, and which aims "to develop rigorous, genuinely interdisciplinary approaches to the empirical study of law." As some commenters have already pointed out, it is not entirely clear what this project has to do with American Legal Realism. I'd like to suggest an answer: essentially nothing.
The actual Legal Realists, to be sure, paid homage to the social sciences, even adopting the rhetoric of the then-dominant behaviorism (e.g., talk about the "stimulus" of the facts of the case), but their actual scholarly practice was almost entirely insulated from the social science of the day--the unfortunate exception being Underhill Moore, who squandered his days recording the parking habits of New Haven drivers, and coming up with forgettable insights like when the parking rules change on a street, it takes awhile for all the drivers to figure that out (though issuing tickets helps!).
This isn't to say that the Realists weren't interested in what the courts do in fact, it's just that their approach to the facts about what courts do almost entirely eschewed social scientific inquiry, and for good reasons I think. The paradigmatic Realist inquiries of the 1920s and 1930s--Oliphant on the promise-not-to-compete cases, Llewellyn on the New York sales cases, Green on "proximate cause" in tort law, Handler on trademark--consisted in careful scrutiny of the underlying facts of lines of cases, bringing out the gap between the official "doctrinal" explanation for the decision and the actual sotto voce norms that seemed to be at work in the judge's thinking. The goal was to discover the non-legal norms that made best sense of the courts' response to recurring "situation-types," i.e., patterns of fact that seemed to elicit the same kind of results. So, in Oliphant's famous example (from an article titled importantly "A Return to Stare Decisis"), he denied that there was a single, general rule about the enforceability of contractual promises not to compete: rather, courts enforced those promises when made by the seller of a business to the buyer, but found ways not to enforce them when made by a (soon-to-be former) employee to his employer. In the former scenario, Oliphant claimed, the courts were simply doing the economically sensible thing (no one would buy a business, if the seller could simply open up shop again and compete); while in the latter scenario, courts were taking account of the prevailing informal norms governing labor relations at the time, which disfavored such promises. A meaningful doctrine of stare decisis could be restored, on this account, by making legal rules more fact-specific, i.e., by tailoring them to the underlying situation-types to which the courts were sensitive. (The extreme version of this hypothesis is vivid in Leon Green's 1931 textbook on torts, which was organized not by the traditional doctrinal categories (e.g. negligence, intentional torts, strict liability), but rather by the factual scenarios—the “situation-types”--in which harms occur: e.g. "surgical operations," "traffic and transportation," and the like. The premise of this approach was that there was no general law of torts per se, but rather predictable patterns of torts decisions for each recurring situation-type that courts encounter.)
That the preceding was the heart of the Realists' "empirical" method explains, of course, why the Realists were so influential in American law: you didn't need social science training to do this kind of analysis, you just needed to be a sensitive and skeptical reader of court opinions, something good lawyers are, well, good at. (Even my late colleague Charles Alan Wright described himself as a "legal realist," for he took the task of his great procedure treatise to be the same as Oliphant's approach to the promise-not-to-compete cases.)
A "new legal realism" would continue the paradigm of scholarship established by the old legal realists, namely, contrasting what courts say they’re doing with what they actually do. "We are all realists now" because this is what so many legal scholars do, including those who know nothing of social science and don't even self-identify as realists. Consider the classic modern debunking of what courts call “the irreparable injury rule” by Douglas Laycock in his 1991 book on the subject. The irreparable injury rule states courts will not enjoin misconduct when money damages will suffice to compensate the victim. Laycock reviewed more than 1400 cases and concluded:
Courts do prevent harm when they can. Judicial opinions recite the rule constantly, but do not apply it...When courts reject plaintiff's choice of remedy, there is always some other reason, and that reason has nothing to do with the irreparable injury rule....An intuitive sense of justice has led judges to produce sensible results, but there has been no similar pressure to produce sensible explanations.
Like the old realists, Laycock finds a disjunction between the “law in the books” and the “law in action,” and, also like the realists, he invokes as an explanation for that disjunction the decision-makers' "intuitive sense of justice." Like Oliphant before him, Laycock seeks, in turn, to reformulate and restate the rules governing injunctions to reflect the actual pattern of decisions by the courts following this intuitive sense of justice.
None of this is to deny the potential value of sound empirical work on law and the legal system. Such work might even illuminate the gap between what the courts say they're doing and what they're actually doing. (The formal political science literature on this subject is, alas, rather disappointing.) It is only to say that the "new legal realism" as the Wisconsin project conceives it has rather little to do with the "old legal realism" which had such a significant impact on American law and legal scholarship.
(I've developed this interpretation of American Legal Realism, with the appropriate scholarly documentation, in various places, but an accessible version is here.)