With respect to the federal government, whose formation he then was championing, Alexander Hamilton assured skeptics during the debates over the new Constitution that state governments would enjoy “one transcendent advantage” — they would retain control over “the administration of criminal and civil justice.” The prosecution of crimes would not be a federal responsibility at all.

That consensus position of the Framers is one that my friends David Rivkin and Lee Casey should have kept in mind before writing “The Wrong Way to Stop Civilian Terror Trials,” a deeply flawed essay published in the Wall Street Journal last week. The two former Reagan Justice Department officers usually offer compelling insights on executive war powers, but their claim that criminal prosecution lies at “the very core of [the president’s] constitutional power” is meritless. It also leads them to an even more specious conclusion: namely, that Congress somehow violates the Constitution by using its power of the purse to block the Obama administration’s efforts to prosecute enemy-combatant terrorists in civilian federal courts.

Messrs. Rivkin and Casey specifically target budget provisions that bar using federal funds to transfer prisoners detained at Guantanamo Bay to the United States. This maneuver, the authors correctly assert, thwarts civilian prosecution. It keeps the terrorists outside federal-court jurisdiction and thus prevents their physical presence at trial, a constitutional right the lawyers reasonably assume the detainees would have in the civilian justice system. (That is, notwithstanding colorable arguments to the contrary, it is a safe bet that federal judges would continue granting the fully panoply of due-process protections to any detainees tried in civilian court.)

From there, though, Rivkin and Casey go off the rails. Congress, the lawyers claim, is violating the Constitution by dictating “whether, when, and where to bring a particular prosecution.” This places the president (and, derivatively, his Justice Department) in a purportedly unusual and untenable position: Though the nation’s “chief federal law enforcement officer and prosecutor,” he is forced “to exercise his discretion in accordance with Congress’s wishes rather than his own.” That, they insist, “violates the Constitution’s separation of powers.”

From its basic premises to its overwrought conclusion, the lawyers’ argument is wrong. There is nothing in the Constitution about the president being the chief federal law-enforcement officer and prosecutor — in stark contrast to Article II’s designation of the president as “commander-in-chief” of the armed forces. Prosecutorial authority, instead, is inferred from Article II’s endowment of all “executive power” in the president. Obviously, since prosecution is an executive function, it is a power the executive branch must have if it is to be exercised by the federal government at all — Congress may prescribe laws, but it may not enforce them. Still, whether and under what circumstances the prosecution power was to be exercised at the federal level are questions the Constitution left entirely up to Congress. The fact that some authority is executive in nature does not make it a “core” presidential power — not if the word “core” is to have any meaning.

Quite intentionally, the Constitution did not establish a federal role in law enforcement. Consistent with Hamilton’s sentiments, James Madison had written that federal powers “will be exercised principally on external objects” — meaning intercourse between our nation and other nations. Madison identified these “external objects” as “war, peace, negotiation, and foreign commerce.” Consequently, the “core” of presidential power is found where Article II intersects with these matters. Thus did Madison elaborate that “the powers reserved to the several states would focus on internal objects” — objects which, “in the ordinary course of affairs, concern the lives, liberties and property of the people,” including the “internal order  . . . of the state.”

The Constitution did not prohibit a federal role in prosecution, just as it did not forbid the creation of federal courts inferior to the Supreme Court. Rather, it left these matters up to the legislature, which would have to find constitutional justifications for any federal intrusions.

In conjunction with establishing the lower federal courts in the Judiciary Act of 1789, Congress created the office of attorney general. President Washington chose Edmund Randolph for the position, making him the fourth cabinet member. Months earlier, among its first orders of business, the first Congress had dealt with what were understood to be the president’s core responsibilities — national defense, foreign affairs, and finance — by establishing the secretaries of war, state, and the treasury.

As if that did not make it clear enough that prosecution was not a core presidential function, the position of attorney general was not originally conceived as prosecutorial in nature. Rather, it was a part-time job with a nominal salary and no office or staff, created because Congress (a) realized the United States would need legal representation in court cases and (b) thought it prudent for the president to have a legal adviser.