Leiter has been a visiting professor of law or philosophy at Yale Law School, University College London, University of Chicago Law School, University of Paris X-Nanterre, University of California, San Diego, and Oxford University. He edited the journal "Legal Theory" from 2000 to 2008, and is editor of the "Routledge Philosophers", a series of introductions to major philosophers, and (with Leslie Green) of "Oxford Studies in the Philosophy of Law". Author Walter K. Olson described Leiter as "left-leaning" in his book "Schools for Misrule: Legal Academia and an Overlawyered America" (Encounter Books, 2011). and Leiter himself has professed sympathy for Marx, stating in an interview that, "On two central issues, Marx was far more right than any of his critics: first, that the long-term tendency of capitalist societies is towards immiseration of the majority (the post-WWII illusion of upward mobility for the "middle classes" will soon be revealed for the anomaly it was); and second, that capitalist societies produce moral and political ideologies that serve to justify the dominance of the capitalist class." Leiter's scholarly writings have been in two main areas—legal philosophy and Continental philosophy—although he has also written about metaethics, religious liberty, and other topics. Philosophical naturalism has been a major theme in both contexts. In legal philosophy, Leiter has offered a reinterpretation of American Legal Realism as embodying a prescient philosophical naturalism and a defense of what he called "naturalized jurisprudence" in his book "Naturalizing Jurisprudence: Essays on American Legal Realism and Naturalism in Legal Philosophy" (Oxford University Press, 2007). Upon publication, Jeremy Horder wrote that the "book will confirm Brian Leiter 's place in the front rank of legal theorists in the world today." Leiter also wrote the entry on "Naturalism in Legal Philosophy" for the "Stanford Encyclopedia of Philosophy". On his view, "philosophers generally should aim to unpack the 'concepts that have been vindicated by their role in successful explanation and prediction of empirical phenomena'" and thus should "'take seriously the…social scientific literature on law…to see what concept of law figures in the most powerful explanatory and predictive models of legal phenomena such as judicial behavior.' This methodological view, however, raises questions about why the legal philosopher should study only judicial behavior and not something else.