Editor’s Note: This is the latest entry in a symposium Just Security is hosting in conjunction with this week’s release of Power Wars: Inside Obama’s Post-9/11 Presidency by Charlie Savage. The series includes posts by Oona Hathaway, Marty Lederman (here and here), and Laura Donohue, with more to come.

Charlie Savage’s new — and quite excellent — book reads as a vindication of the decision to go to law school. It tells the story of the ascendancy of law — and hence lawyers — in the upper echelons of the Obama administration. This is, after all, the inevitable result of what Savage describes (accurately, I believe) as Obama administration’s overriding emphasis on rule of law.

From questions of who can be lethally targeted, when and where individuals can be detained without charge, and the scope of foreign surveillance programs, the legal answer is the policy answer. In many ways this is exactly as it should be. In a well functioning executive branch, the lawyer tells the policymakers the legal limits of possible policy proposals. And thus — assuming a set of law-abiding policymakers — the legal advice sets the outer boundaries of what can be done.

But there are two key twists in the context of national security lawmaking, particularly in world where the the nation faces a shadowy, ever morphing, and potentially existential threat. First, the overriding goal of the national security apparatus is, quite appropriately, to protect the nation from this threat. In a range of situations national security policy makers are — in the words of General Michael Hayden — going to get chalk-dust on their cleats. Or as Savage puts it: “[I]n practice, if the lawyers say it is permissible to take some disputed action that might, even marginally, reduce the risk of a terrorist attack, policy makers find it very difficult not to take that action.”

Second, the story of lawyer as authoritative limit-setter invokes, at least implicitly, the notion of some knowable, identifiable, natural law to apply — or at least a set of clear precedent to draw upon. But the myriad targeting, detention, and surveillance questions to which national security lawyers are now being asked to decide raise novel, complicated, and contested legal issues. Put simply, there is — as elucidated by some of the inter-agency legal battles captured so well by Savage — often more than one way to apply and interpret the law as applied to a conflict between a state and transnational terrorist enemy and a digital, globally interconnected Internet. There is, as a result, often no definitive “right” answer to identify and apply.

Thus, whereas the lawyer’s advice has a source of authority as grounded in law, it is de facto policy guidance as well. As Savage describes it, “the legal debate sometimes substitutes for the policy debate … with momentous consequences for the safety of the country, for human rights around the world, and for America’s continuing experiment in self-government.”

Now to be sure, there are exceptions to this narrative. Savage, for example, describes the decision not to send more detainees to Guantánamo — even though it would have been lawful to do so in certain circumstances. And he suggests that the then-involved lawyers were prepared to sanction, as necessary and proportionate, the bombing of bin Laden’s compound — an action that would have killed an estimated 50 to 100 additional people. But the option was taken off the table for policy reasons, namely the almost inevitable backlash resulting from the high number of civilian casualties.

I also reject the conclusion that the national security lawyers that succeed simply find ways to approve what the operators want to do. Quite to the contrary, Savage’s book is also full of examples in which legal limits constrained policy. Examples include the 2011 decision not to classify al-Shabaab as an associated force of al-Qaeda, the refusal to disregard congressional limitations on transferring out Guantánamo detainees, and the refusal to transfer Ali Musa Daqduq, the last remaining US-held detainee in Iraq in 2011 who was of particular interest to the US government, out of Iraq without Iraqi consent.

Rather, I think the book provides an important reminder of four key points, some obvious, some less so:

First, the lawyers — particularly in an administration committed to rule of law as a key, overriding value — wield an enormous and often unspoken power. The could often substitutes for the should, with the result being that the national security lawyer becomes the de facto policy maker. (This is also the point made by Margo Schlanger in her excellent article, Intelligence Legalism).

Second, the legal answers are often unsettled, meaning that perspective, background, and inclinations of the lawyers in the advice-providing roles matters. The lawyer’s view on executive power, the nature and scope of armed conflict, and the application of human rights law — all highly contested legal issues — often, after all, provide the de facto policy answer.

Third, and relatedly, it matters who gets a seat at the table. Although there were exceptions (see Marty’s post and Savage’s additional reporting on the bin Laden operation for example), the book is full of examples of active legal engagement — and sparring — between members of Obama’s legal team. Harold Koh, then-Legal Adviser at the State Department, and David Barron, then-acting head of DOJ’s Office of Legal Counsel, fought over the scope of executive power; Koh and Jeh Johnson, then-General Counsel for the Pentagon, debated the scope of associated forces; and Defense and State Department lawyers fought the Department of Justice (and lost) over the litigation risk associated with the defense of material support and conspiracy convictions by military commission. This is how it should be. While disagreement is no doubt frustrating and time-consuming to deal with, it also helps ensure (generally) better and more fully vetted results.

Finally, the debate on these key legal — and policy — principles should not be limited to a handful of executive branch lawyers. Given the power of the law as policy, transparency is key. The executive branch should do as much as it possibly can — and more than it has done to date — to share, debate, and defend the legal views it adopts.