At one time there was among American political scientists something of a consensus about the role of the world's legislatures in the policy-making process. The United States Congress, so the conventional wisdom went, was a legislature with a central policy-making role. Even while many observed and lamented what seemed to be an increasing tendency toward presidential domination of congressional decision-making, they found the rest of the world's legislatures even more deficient as policy-making bodies. The policy-making role of European legislatures was viewed either as permanently subordinated to political parties, cabinets, and bureaucracies or at best in decline relative to these institutions. As for legislatures in Third World and in Marxist political systems, the issue for these institutions was neither their centrality nor their decline, but rather their political irrelevance. Not only did these legislatures play less of a policy-making role than the modal European case, they often were blatantly manipulated and intimidated by military, civilian and partisan bureaucracies. The consensual view was that these legislatures existed for the primary purpose of providing a democratic facade for authoritarian political systems (see Packenham, 1970).

Beginning in the late 1960s, however, students of legislative behavior began to develop a more sophisticated sense of what legislatures did and how they affected public policy. While admitting that most legislatures seldom made the major policy decisions and usually followed the lead of other institutions, more subtle ways by which legislatures influenced public policy were detected.