American law students learn about formalism and instrumentalism early on—although those particular terms may not be introduced explicitly in classroom discussion. Many law students hunger for “black letter law”: they are looking for legal rules that can be memorized and applied to the facts in a more or less determinate (or even “mechanical”) fashion. But in most law school classrooms, this hunger is not satisfied.
Instead, the discussion is likely to focus on another set of questions: What should the rule be? What is the purpose of the rule? Would the application of the rule to these facts serve its purpose? Does that rule make sense? And so on. Of course, different professors have different ideas about what makes for good legal rules. Some emphasize good consequences—perhaps as defined by the economic concept of efficiency. Others might emphasize considerations of fairness or distributive justice. Many are progressive or liberal; a few are conservative or libertarian.
In constitutional law, “black letter law” sometimes seems to disappear entirely. Instead, there is a Supreme Court that seems to act as some sort of super-legislature, resolving the great questions of the day, whether it be “Who shall be President?” or “May states criminalize sexual activity between persons of the same sex?” or “Shall abortion be legal?”
Moreover, students quickly learn that the constitutional text does not seem to be much of a barrier to a result that the Court really wants to reach. An obvious example is Bolling v. Sharpe in which the Supreme Court applied the substance of the equal protection clause to the federal government—even though it is unmistakably clear that the 14th amendment applies only to the state.