One reason legal history is more interesting than it was several decades ago is the increased role of interest groups in our accounts of legal change. Diverse movements including law and society, critical legal theory, comparative law, and public choice theory have promoted this development, even among writers who are not predominantly historians. Nonetheless, in my own survey course in American legal history I often push back. Taken too far, interest group theorizing becomes an easy shortcut for assessing legal movements and developments without fully understanding the ideas behind them.
Intellectual history in the United States went into decline because its practitioners often wrote as if the history of ideas drove everything else, either disregarding or minimizing the role of interest groups. In the process it became viewed as inherently conservative because its source materials came almost exclusively from elite white males. On the other side, social and economic history have been driven by impulses originating from both the left and the right that sees policy as little more than the outcome of conflict among interest groups. Further, these preference are generally "naked" in the sense that they reveal little more than the desires of each individual for wealth, stability, social status, or other recognition. Articulated ideas are little more than rationalizations, and the public processes that make legal rules are largely a zero sum game.
I try to instill in my students the idea that legal history is a much more complex process in which ideas and preferences interact. In differing areas and at different times one may dominate over the other, but almost never permanently. Further, ideas lead to preferences just as much as the other way around.
Teaching legal history in this fashion is more challenging to both the instructor and the students because it requires that ideas be taken more seriously. One cannot simply pass a hand over an entire area such as business policy and proclaim it to be the result of Social Darwinism, populism, labor and the surge in immigration, or some other interest group movement. I certainly do not expect my students to become experts in Calvinism, the social contract, classical political economy, genetic determinism, Freud, or the many other areas that wander into and out of my legal history course. But I do expect them to learn enough to take them seriously, and to understand that these intellectual ideas were as powerful to those who encountered them as the ideas that we hold today.