"Inter arma enim silent leges," holds the hoary Roman maxim thought to originate with Cicero: In time of war, the laws fall silent. In our own era, few proponents of that doctrine have been as influential or forceful as Berkeley law professor John Yoo, who in the wake of the terrorist attacks of September 11, 2001, worked within the Office of Legal Counsel at the Justice Department to lay the legal foundations for the Bush administration's approach to the war on terror. Despite repeated pleas from civil liberties groups, crucial memoranda authored by Yoo, justifying controversial tactics ranging from coercive interrogation to warrantless surveillance, remained closely guarded secrets—until Monday.

The Department of Justice, citing the "legitimate and substantial public interest" in these opinions, today released a series of nine documents not previously available to the public: six legal opinions issued by Yoo and his contemporaries in 2001-2002, and two more recent memoranda repudiating many of those opinions in strikingly sharp language. Among them are several opinions—two presented in full, one in summary—offering a theoretical basis for President Bush's decision to authorize a program of extrajudicial wiretapping and data mining by the National Security Agency.

The first of these opinions is dated September 25, 2001, just weeks after the 9/11 attacks. In it, Yoo endeavors to respond to an almost astonishingly modest question: Whether it would be consistent with the Constitution to amend the Foreign Intelligence Surveillance Act so as to permit the secret FISA court to authorize (under somewhat more lax standards than apply in criminal cases) surveillance of agents of foreign powers when the gathering of foreign intelligence was "a purpose" of the surveillance. The statute at the time required that this be the "primary purpose" of FISA intercepts, though the USA PATRIOT Act, in what might be seen as something of a compromise, would soon change the standard to a "significant purpose." (Perhaps ironically, this memo is addressed to then-Associate Deputy Attorney General David Kris, later a prominent critic of the legal rationalizations for the warrantless surveillance program, and now Barack Obama's pick to head the National Security Division at Justice.)

Having asserted that the Constitution assigns the president not merely the power but the obligation to act in defense of national security Yoo then portentously observes that "FISA itself is not required by the Constitution, nor is it necessarily the case that its current standards match exactly to Fourth Amendment standards."

Yoo rather perfunctorily concludes that there would be no constitutional barrier to such an amendment. The FISA court, after all, could still determine whether a warrant application simply sought to invoke foreign intelligence as a pretext for a primarily criminal investigation, in violation of the Fourth Amendment. The proposed amendment "would simply allow the Department to apply for FISA warrants up to the limit permitted by the Constitution, as determined by the FISA court." In other words: it can't hurt to ask.

But Yoo then veers from his assigned task into what can only be described as a lengthy and unsolicited digression, laying out his view of the primacy of the president in the national security arena, and the scant limits on presidential discretion to order surveillance targeting foreign terrorists. He writes:

The text, structure and history of the Constitution establish that the Founders entrusted the President with the primary responsibility, and therefore the power, to ensure the security of the United States in situations of grave and unforeseen emergencies. Intelligence gathering is a necessary function that enables the President to carry out that authority...

The implications of constitutional text and structure are confirmed by the practical consideration that national security decisions often require the unity in purpose and energy in action that characterize the Presidency rather than Congress...

As the Commander in Chief, the President must be able to use whatever means necessary to prevent attacks upon the United States; this power, by implication, includes the authority to collect information necessary for its effective exercise.

Having asserted that the Constitution assigns the president not merely the power but the obligation to act in defense of national security Yoo then portentously observes that "FISA itself is not required by the Constitution, nor is it necessarily the case that its current standards match exactly to Fourth Amendment standards."

Breaking the shackles of the Fourth Amendment

The chain of reasoning to this end is a truly spectacular exercise in casuistry, which for purposes of brevity, we might dub the "if you can shoot 'em..." argument.

But Yoo was only getting warmed up. Less than a month later, on October 23, Yoo would urge the president to cast off the shackles of the Fourth Amendment entirely—jettisoning not only the obligation to seek probable-cause warrants, but even the standard of "reasonableness." In an opinion finding that the Posse Comitatus Act's ban on the domestic deployment of the armed forces was inapplicable to counterterrorist operations, Yoo argues that "however well suited the warrant and probable cause requirements may be as applied to criminal investigations or to other law enforcement activities, they are unsuited to the demands of wartime and the military necessity to successfully prosecute a war against an enemy." Rather, he writes, "the Fourth Amendment does not apply to domestic military operations designed to deter and prevent foreign terrorist attacks."

Yoo is quite explicit that the president is "free from the constraints of the Fourth Amendment" with respect to a broad range of activities, explaining that "military action might encompass making arrests, seizing documents or other property, searching persons or places or keeping them under surveillance, intercepting electronic or wireless communications, setting up roadblocks, interviewing witnesses, and searching for suspects." The National Security Agency, recall, resides within the Department of Defense.

The chain of reasoning to this end is a truly spectacular exercise in casuistry, which for purposes of brevity, we might dub the "if you can shoot 'em..." argument. Omitting the ample footnotes—heavy on precedent from the Civil War and the War of 1812—it runs roughly as follows. The Fourth Amendment clearly doesn't apply to overseas military operations. (It has precious little application of any sort overseas, but leave that.) And on the home front, the military can clearly use deadly force against invading armies or insurrectionist forces. Moreover, in self defense against a foreign army, the government can even torch private facilities—like fuel reserves—that might be used by an invading force. Since all of these defensive actions entail more severe deprivations of liberty than mere surveillance, and since none of them require prior approval of a magistrate, Yoo would have us infer that the Fourth Amendment is not merely attenuated in the face of the exigencies of national security, but wholly inapplicable.

Finally, one of the later memoranda, authored by Deputy Assistant Attorney General Steven Bradbury in January of this year, summarizes Yoo's interpretation of the Foreign Intelligence Surveillance Act as articulated in a February 2002 opinion. Though that document remains classified, the summary explains Yoo's view that FISA must be interpreted as placing no limits on the president's power to authorize surveillance in the interest of national security. This is, as Bradbury notes with a certain deadpan restraint, "problematic and questionable, given FISA's express references to the President's authority." Other OLC memos drawing similar conclusions are described as "not supported by convincing reasoning."

Indeed, in the waning days of the Bush administration, Justice Department attorneys had occasion to revisit much of Yoo's legal reasoning. Though the summary memos prepared in late 2008 and early 2009 say the DOJ has not relied on the disavowed opinions since 2003, they emphasize, lest there be any doubt, that several of these "doubtful" arguments "should not be relied upon or treated as authoritative for any purpose." Such adjectives as "unconvincing," "not satisfactory," and "erroneous" are liberally applied.

The "if you can shoot 'em" argument—in the terrifying eventuality that anyone found it superficially plausible—is among the casualties. With more of that characteristic deadpan restraint, the 2009 memo concludes that Yoo "inappropriately conflates the Fourth Amendment analysis for government searches with that for the use of deadly force." In other words, a "highly fact-dependent" self-defense justification may be invoked in particular circumstances characterized by a severe threat of imminent harm—an invading army, or even a homicidal thug brandishing a weapon at a police officer. This does not, in fact, license a broad inference that whole constitutional provisions cease to apply altogether whenever there is a general state of heightened threat.

Not all of the specious arguments familiar from the early days of the FISA debates are cast by the wayside, however. The 2009 memo also notes that the OLC's current view, superseding Yoo's now disfavored arguments, is that the NSA program was justified because the congressional Authorization for the Use of Military Force empowered the president to circumvent FISA. It is one of Yoo's former interlocutors, David Kris, who has most decisively dispensed with that argument. As Kris notes, the PATRIOT Act, enacted nearly simultaneously with the AUMF, itself amended FISA, which contains very limited provisions detailing the special powers the executive branch may exercise in the immediate aftermath of a declaration of war. This, Kris argues, makes it very hard to credit the notion that Congress intended to create an enormous implicit loophole in the FISA statute, while doing nothing of the sort in a contemporaneous explicit revision of FISA that also reasserted the statute's privileged status as the "exclusive means" for foreign intelligence collection.

If it is unsettling to contemplate the speciousness of the legal arguments that supported a radical expansion of executive surveillance power, we can at least take some solace in knowing that the most dangerous of these thin rationalizations are finally out in the open—and openly rejected by the Department of Justice. "Inter arma enim silent leges" may have a noble provenance, but it bears remembering what became of Rome.