Over at the University of Chicago’s Law School faculty blog, respected liberal legal scholar (and U of C faculty member) Cass Sunstein has posted an informative item on the meaning of the “unitary executive” (h/t Instapundit)…

Those who believe in a unitary executive need not think that the president can defy the will of Congress, or torture people, or make war on his own. The principle of a “unitary” executive involves only one thing: The president’s hierarchical control over implementation (“execution”) of federal law….
In American constitutional law, the idea of a unitary executive is nothing new. It goes all the way back to the founding. The Constitution does not create a “plural” executive; Article II, section 1 vests executive power in one person, the president of the United States. The decision to create a unitary rather than plural executive was debated and decided. So in a way, everyone agrees that ours is a unitary executive. (Franklin Delano Roosevelt insisted on that point, and was especially dismayed when the Supreme Court ruled otherwise in its decision holding that the heads of the FTC are not the president’s at-will employees)….
The most important point is that the claim for the unitary executive is not a general claim about the President’s power to act on his own or to contradict the will of Congress. You can believe in a strongly unitary executive branch while also believing that the President cannot make war, or torture people, or engage in foreign surveillance without congressional authorization. You can also believe that the president can do a lot on his own, or a lot in violation of Congress’ will, while also accepting the view that Congress can create independent agencies and independent prosecutors. In short, the debate over the unitary executive is an important but narrow one, and it is a small, distinct subpart of the general debate over presidential power.