The program of warrantless NSA wiretapping (and data mining) authorized by the president shortly after the 9/11 prompted a flurry of intense debate over its legality when it was disclosed by The New York Times back in 2005. Those arguments have, by now, been so thoroughly rehearsed that there’s not a whole lot new to say about it.

But like Monty Python’s Black Knight, some of those old arguments keep popping up — as evidenced by John Eastman’s contribution to the Cato Unbound roundtable on the digital surveillance state we held last month. So while the roundtable’s over, I thought it would be convenient to round up a compact version of the main arguments in one place, for the convenience of folks who might not want to slog through the many law review articles that have been written on the subject.

The touchstone for modern analysis of executive war powers is, by general consensus, the tripartite schema elaborated by Justice Jackson in his concurrence in the Youngstown steel seizure case :

1. When the President acts pursuant to an express or implied authorization of Congress, his authority is at its maximum, for it includes all that he possesses in his own right plus all that Congress can delegate. In these circumstances, and in these only, may he be said (for what it may be worth) to personify the federal sovereignty. If his act is held unconstitutional under these circumstances, it usually means that the Federal Government, as an undivided whole, lacks power….

2. When the President acts in absence of either a congressional grant or denial of authority, he can only rely upon his own independent powers, but there is a zone of twilight in which he and Congress may have concurrent authority, or in which its distribution is uncertain….

3. When the President takes measures incompatible with the expressed or implied will of Congress, his power is at its lowest ebb, for then he can rely only upon his own constitutional powers minus any constitutional powers of Congress over the matter…. Presidential claim to a power at once so conclusive and preclusive must be scrutinized with caution, for what is at stake is the equilibrium established by our constitutional system.

Using this as our starting point, it becomes clear that an analysis of the NSA program entails answering a series of distinct (though related) questions. First, we need to determine which level of the Youngstown schema applies. If we’re in Youngstown’s Category I, then the NSA program was illegal only if it exceeded the constitutional constraints on government surveillance established by the Fourth Amendment. If, on the other hand, we’re in Category III, a constitutionally permissible surveillance program might nevertheless be illegal. So I’ll consider three questions in turn: Did the NSA program violate federal statute? If so, does the statute trump whatever inherent power the president might enjoy as commander in chief in this context? Finally, does the program as it’s been publicly described violate the Fourth Amendment? An affirmative answer to either the first pair of questions or the third will entail that the NSA program was illegal.

The AUMF

The statutory question may seem like something of a no-brainer: The Foreign Intelligence Surveillance Act of 1978 states explicitly that its procedures establish the “exclusive means” by which domestic electronic surveillance for foreign intelligence purposes. In this case, the obvious answer is the right one. But the Justice Department has attempted to claim that Congress cleverly managed to repeal the “exclusive means” language without telling anyone about it back in 2001, when it passed the Authorization for the Use of Military Force against the perpetrators of the 9/11 attacks. Probably the most decisive demolition of that argument was offered by David Kris, who currently heads the National Security Division at the Department of Justice, but it’s worth reviewing briefly why this argument is so implausible.

The central problem with reliance on the AUMF is that FISA itself contains a provision providing a 15-day surveillance grace period following a declaration of war. As the legislative conference report explains, this was intended to provide time for Congress to consider whether any wartime modifications to the FISA structure were necessary. Plainly, then, Congress did not imagine or intend that a declaration of war (or “authorization of force”) would in itself implicitly loosen FISA’s fetters beyond that grace period.

Moreover, Congress has repeatedly amended FISA since the 9/11 attacks, both in the PATRIOT Act passed almost simultaneously with the AUMF, and in subsequent legislation over a period of years. As Glenn Greenwald recounted in his lead essay for the Cato roundtable, it has expanded government surveillance powers in a variety of ways, but none of these prior to the Protect America Act of 2007 (superseded by the FISA Amendments Act of 2008) approached the breadth of the NSA program, and even these establish at least a modicum of judicial oversight, however inadequate. Again, this history sits uneasily with the premise that Congress understood itself to have authorized such broad domestic surveillance when it passed the AUMF.

Indeed, as former Senate Majority Leader Tom Daschle explained in a Washington Post op-ed shortly after the revelation of the warrantless wiretap program, the Senate explicitly rejected language sought by the White House that would have extended the authorization to actions within the United States. Then–Attorney General Alberto Gonzales has publicly acknowledged that the Bush Administration contemplated asking for a more specific amendment to FISA authorizing something like the NSA program, but concluded that it would be “difficult, if not impossible.” We are being asked to believe, in other words, that Congress intended to implicitly grant authority that the administration was certain would be refused had it been requested overtly. It is, as Justice Frankfurter put it in Youngstown, “quite impossible… to find secreted in the interstices of legislation the very grant of power which Congress consciously withheld.”

Basic principles of statutory construction disfavor inferring implicit repeal of specific statutory language from more general authorizations, except in the face of “overwhelming evidence” of congressional intent—and the Court has accordingly rejected parallel arguments in several recent War on Terror cases, as in Hamdan v. Rumsfeld, where the court found “nothing in the text or legislative history of the AUMF even hinting that Congress intended to expand or alter the authorization” for military commissions spelled out in the Uniform Code of Military Justice.

The evidence here is indeed overwhelming, but it uniformly cuts against the fanciful proposition that Congress somehow enacted a kind of sub silentio repeal of FISA. I’m inclined to assume this argument was offered primarily because of an understandable reluctance to rely entirely on a radical theory of inherent and preclusive executive powers, to which I turn next.

The President’s Inherent Authority

The first thing to observe with respect to claims of inherent executive authority here is that if we exclude non-binding dicta, the evidence for a constitutional power to conduct warrantless domestic surveillance for foreign intelligence purposes is almost wholly negative. That is to say, it turns on inferences from questions the Supreme Court has declined to directly address rather than on its affirmative holdings. As we’ll see, this is a thin reed on which to hang ambitious claims.

Consider, for instance, the so-called Keith case. In addressing the scope of presidential power to authorize warrantless surveillance against domestic national security threats, the majority noted that they had “not addressed, and express no opinion as to, the issues which may be involved with respect to activities of foreign powers or their agents.” But in that very case, the unanimous majority held that a warrant was required in cases involving domestic national security threats, resolving a lacuna expressed in very similar language in a footnote to a previous ruling involving wiretaps:

Whether safeguards other than prior authorization by a magistrate would satisfy the Fourth Amendment in a situation involving the national security is a question not presented by this case.

The arguments deployed against unchecked executive discretion in Keith clearly have substantial cross-application to the War on Terror, which in many respects bears as much resemblance to those domestic threats as it does to traditional nation state–sponsored espionage and warfare. It will suffice to note, however, that declining to foreclose a power because the fact pattern under consideration provided no occasion to consider the distinct issues involved, as the Court did in both Katz and Keith, is not at all the same as affirmatively asserting it, let alone defining its scope—a point to which I’ll return in the next section.

Nevertheless, let’s suppose arguendo that there is some such inherent power, whether broad or narrow. Eastman and other defenders of the NSA program stil err in conflating inherent power with preclusive or indefeasible power. As a simple conceptual matter, this cannot be right, or else the third Youngstown category would collapse into the second: If all “inherent” presidential powers were per se immune to Congressional limitation, Category III would be superfluous, since it would never yield a result different from analysis under Category II.

Fortunately, we need not restrict ourselves to conceptual analysis, because precedent and practice both speak directly to the question, and both support robust legislative power to constrain even those presidential powers grounded in Article II. The legislature has, from the founding era on, assumed that its Article I power to make “rules for the government of the land and naval forces” enabled it to cabin the discretion of the commander in chief, often in frankly picayune ways, by establishing general rules limiting the conduct of a conflict. Prior to the Truman administration there was little indication that presidents saw this as encroaching upon sacrosanct executive prerogatives. Even Lincoln—probably the most obvious early example of a wartime president acting without or contrary to statutory authority—did not claim some general constitutional power to defy Congress. Rather, he argued that when hostilities commenced during a congressional recess, he had acted as he thought necessary given the impracticality of securing advance approval, while acknowledging that it fell to the legislature to ratify or overrule his judgment once it reconvened.

In the few cases where the Supreme Court has had occasion to rule on the scope of executive power at “lowest ebb,” it has repeatedly confirmed that federal law binds the president even in war. In Little v. Barreme, during a conflict with France, the Court found that a specific Congressional authorization for the seizure of ships bound to French ports rendered invalid an executive order that also permitted seizure of ships bound from those ports. And this was so, the Court noted, even though the president’s own commander-in-chief powers would have permitted him this discretion had Congress not spoken. Since the inauguration of the War on Terror, the Court has reaffirmed the validity of such statutory limits on executive discretion, as in Hamdan. Bush’s own Office of Legal Counsel ultimately repudiated a series of memos, penned by John Yoo, that had relied on a more expansive conception of executive power to justify the administration’s War on Terror programs, concluding that they were “not supported by convincing reasoning.”

There is, by general consensus, some “preclusive core” to the executive’s commander-in-chief authority. This includes, at the least, a prerogative of “superintendence”: Congress could not appoint Nancy Pelosi commander of U.S. forces in Afghanistan and forbid the president to remove her. Most commentators see it as similarly foreclosing efforts to achieve the same end by a series of micromanagerial statutes commanding specific tactics be employed at particular times. But the notion that this preclusive core encompasses discretion to unilaterally disregard a general statutory framework governing protracted electronic surveillance of U.S. persons on American soil is simply insupportable in the face of both history and precedent. The argument is, if anything, more absurd when it comes to the government’s illegal acquisition the statutorily protected calling records of tens of millions of Americans, the vast majority of whom obviously have no ties to terrorism or Al Qaeda. Attempts to stitch together a countervailing line from desultory snatches of language about the president’s role as “sole organ” in foreign affairs are entertaining as a sort of exercise in experimental Burroughsian cut-up narrative, but as legal analysis they seem pretty desperate.

The Fourth Amendment

Finally, we turn to the Fourth Amendment. I will, for the most part, consider how the Fourth Amendment applies to the NSA surveillance program prior to the 2008 passage of the FISA Amendments Act.

As Eastman notes, while in most contexts the prohibition on “unreasonable searches and seizures” requires surveillance to be authorized by a probable cause warrant based on individualized suspicion, there are a variety of circumstances in which warrantless searches may nevertheless be reasonable. While this is not the place to conduct a detailed survey of such “special needs” exemptions, such exceptions tend to involve cases in which the subjects of the search are already understood to enjoy a diminished expectation of privacy (students in school), where the searches are standardized and minimally intrusive, where the targets are in a position to raise challenges before a neutral magistrate if necessary, and where prior court authorization would be highly impractical. No exception that I am aware of can plausibly be stretched so far as to permit sustained, discretionary, warrantless electronic surveillance of members of the general population—a method recognized to be so intrusive that in the criminal context, federal statute requires investigators to meet a higher standard than applies to ordinary physical search warrants.

It’s worth noting in passing that the existence of the statutory FISA framework is at least arguably relevant to the Fourth Amendment analysis here. What measures are “reasonable” will often depend on context, and upon the available alternatives: The use of lethal force in self-defense might be found reasonable as a last resort, but not when the victim has an easy avenue of escape or a taser handy. Similarly, if the only alternative to conventional criminal courts were warrantless surveillance—if Congress had made no provision for a highly secretive court to consider classified applications under secure conditions, with ample flexibility in cases of emergency—one might be more inclined to sympathize with some degree of executive improvisation. In light of the elaborate mechanisms Congress has provided, an appeal to impracticality is considerably less compelling.

But let’s bracket that for the moment, and again suppose for the sake of argument that the president has some inherent authority to conduct warrantless domestic wartime surveillance. Let’s further assume away any statutory problems. Can the NSA program be squared with the Fourth Amendment injunction that searches be reasonable, based on what little we know of it? It seems highly unlikely.

Multiple accounts suggest that the NSA program involved algorithmic selection of surveillance targets, possibly triggered by keywords within the communications themselves, almost certainly based on pattern analysis of calling records or other transactional data. The result, according to the Bush administration, was that the international communications of approximately 500 persons within the U.S. were being intercepted at any given time. Since the program operated for several years, both before and after being disclosed, a conservative estimate would place the total number of persons subject to surveillance in the thousands, and most likely in the tens of thousands.

What did all this spying yield? In 2006, under the headline “Surveillance Net Yields Few Suspects,” the Washington Post reported:

Fewer than 10 U.S. citizens or residents a year, according to an authoritative account, have aroused enough suspicion during warrantless eavesdropping to justify interception of their domestic calls, as well.

Nearly all the “leads” produced by the program appear to have been dead ends. Indeed, despite the assurances of the Bush administration that the NSA program had saved thousands of lives, a postmortem review by the intelligence community’s Inspectors General found that officials they spoke to “had difficulty citing specific instances where [NSA program] reporting had directly contributed to counterterrorism successes,” though a classified version of the report apparently cites a handful of instances in which the program “may have contributed.”

As a point of reference, the government’s reporting suggests that under criminal wiretap orders, about 30 percent of intercepted communications contain incriminating content. Since “minimization” of innocent communications is necessarily imperfect, and since even the most hardened criminals presumably spend most of their time conversing about more mundane matters, the number of targets engaged in at least some incriminating communication is clearly far higher. That’s what one would expect when evidence establishing “probable cause” must justify surveillance—and Bush officials have claimed the NSA program’s targeting met the same standards. The evidence suggests otherwise.

I’m happy to grant that we should accept a somewhat lower “hit rate” when interception is geared toward protecting the nation from major terror attacks. But if the requirement that searches be “reasonable” is not to be rendered completely vacuous, or totally severed from even a diluted standard of “probable cause,” there must be some substantive test of whether such highly intrusive techniques are actually in service of that vital state interest. It cannot possibly be enough to simply observe that the president has uttered the magical incantation “war on terror.” And it cannot possibly be enough that a program involving interception of the private conversations of thousands or tens of thousands of U.S. persons “may have contributed” to a handful of successful investigations. The question is closer with respect to post-FISAAA programs of interception, which are at least subject to some modicum of independent oversight, but unless we have gotten vastly better at sifting the guilty from the innocent, grave constitutional doubts should remain.