Harry Truman felt sorry for Dwight Eisenhower. If Truman, merely a failed haberdasher, after all, bristled at the obstacles to his presidential authority, imagine how aggravated his successor, a former five-star general, would be. Tapping on his desk in the Oval Office, Truman remarked, “He’ll sit here and he’ll say, ‘Do this! Do that!’ And nothing will happen. Poor Ike—it won’t be a bit like the Army.”

A promotion to commander in chief, in Truman’s estimation, would limit Eisenhower’s power. His orders, delivered as an elected official, would lose the sir-yes-sir acceptance that they received in the military. To hear Truman tell it, the president could do little more than implore: “I sit here all day trying to persuade people to do the things they ought to have sense enough to do without my persuading them. ... That’s all the powers of the president amount to.”

Said the man who dropped the bomb, who desegregated the military by executive order, who sent troops into battle in Korea without a congressional declaration of war, who imposed wage and price controls on defense-related industries, and who authorized a federal takeover of steel mills.

Both in his displays of power and in his sense of weakness, Truman reflects the dichotomy of the modern presidency that the Law School’s Eric A. Posner, U-High’84, describes in The Executive Unbound: After the Madisonian Republic (Oxford University Press, 2011). Posner, the Kirkland and Ellis professor of law, and coauthor Adrian Vermeule of Harvard agree with a common view that the constitutional separation of powers, of which James Madison was a founding architect, has become a historical relic. Unlike critics of that development, they don’t have a problem with it, claiming that political considerations serve as de facto checks and balances every bit as strong as legal constraints.

Posner and Vermeule acknowledge that the executive branch, including the president and independent agencies such as the Federal Reserve, supersedes the legislative and the judicial branches under almost any circumstances. As long ago as 1948, Clinton Rossiter’s Constitutional Dictatorship (Princeton University Press) noted the shifting balance of power. In The Imperial Presidency (Houghton Mifflin, 1973), Arthur Schlesinger Jr. further entrenched what has become accepted wisdom: a sweeping expansion of executive power, dating roughly to World War II, has eroded the constitutional foundation.

The exercise of unilateral presidential power spans foreign and domestic policy and crosses party lines. George W. Bush, for example, issued an executive order limiting federal funding for embryonic stem-cell research. And in June, Barack Obama halted the deportation of undocumented immigrants brought to the United States as children, a defining facet of the Dream Act that Congress had voted down.

Over the past decade, antiterrorism policies under Bush and Obama—torture, indefinite detention, warrantless surveillance, targeted killings—have intensified criticism from those who believe the presidency has become an unaccountable dictatorship. Aziz Huq, a UChicago assistant professor of law, and New York University’s Frederick A. O. Schwarz Jr. examined the Bush administration’s post-9/11 policies in their 2007 book, Unchecked and Unbalanced: Presidential Power in a Time of Terror (The New Press). They argue that “monarchist claims of executive power” circumvent constitutional checks and balances.

That’s where Posner and Vermeule diverge, dismissing as hyperbole concerns that equate the presidency with a monarchy. They call the most strident criticism of expansive executive power “tyrannophobia.” Such irrational fear, the authors say, ignores the democratic forces constraining the president as much, if not more, than the constitutional framework: politics and public opinion. Truman felt weak not because he lacked the discretion to act in matters foreign and domestic, military and civilian, social and economic. He felt weak because those actions were subject to critical, often hostile, evaluation—and ultimately subject to an election.

Presidents have to act within the boundaries of what the public will accept to maintain the credibility to govern. In practice, Posner and Vermeule argue, the standard that restrains a president’s imperial impulses is not constitutional legality but political legitimacy. Citing legal theorist Frederick Schauer, the authors write, “If the underlying action is unpopular, then citizens will treat its illegality as an aggravating circumstance, but if the underlying action is popular, its illegality usually has little independent weight.”

During national emergencies—9/11, the 2008 financial crisis—the legal leeway increases. The executive branch alone has the capacity to respond with sufficient speed and resources to combat an imminent threat. With enough political support, an administration can expect to be unfettered by Congress or the courts. “In crises, legality and legitimacy diverge, and legitimacy prevails,” Posner and Vermeule write, “but this suggests that even in normal times, where they happen to coincide, legitimacy may be the only force that matters.”

Richard Nixon admitted as much in 1977, when he told interviewer David Frost, “If the president does it, that means it’s not illegal.” In the wake of Watergate, Congress perceived a weakened executive branch and enacted statutes intended to reinforce the constitutional restraining walls. But subsequent administrations overlooked the restrictions without consequence. Bill Clinton, for example, ignored the 1973 War Powers Resolution when he allowed American military action in Kosovo to persist beyond the 60-day grace period the law granted without congressional approval.

Although hardly an aberration in modern history, Clinton’s actions exemplified the authority inherent in the office. Even while embroiled in the Monica Lewinsky investigation, his political capital presumably depleted by the scandal, the New York Times noted Clinton’s continued exercise of power: “a blizzard of executive orders, regulations, proclamations, and other decrees to achieve his goals, with or without the blessing of Congress.” He issued an order instituting key provisions of antitobacco legislation, for example, that the Senate had rejected. In Madison’s Nightmare: How Executive Power Threatens American Democracy (University of Chicago Press, 2009), Ohio State law professor Peter M. Shane writes that Clinton “made claims for the presidential control of domestic regulatory policy making that were nearly unprecedented in substance and certainly unparalleled in volume.”

Historians trace the steady growth in such unilateral executive action to Franklin D. Roosevelt’s administration, beginning a trend that has continued—or, as some have argued, accelerated—under Bush and Obama. Posner sees a contradiction in the criticism of that evolution.

He believes the public values stronger federal regulation of national concerns such as the economy and the environment, a governmental structure that requires concentrated executive power. Centralized authority, The Executive Unbound argues, makes the United States not a traditional “rule of law” nation but an “administrative state.” For the government to function under those circumstances, Posner says, the executive branch must be “first among equals.” To him that accumulation of authority is not a harbinger of tyranny, or necessarily negative at all, but “a natural development, reflecting public opinion and the institutional advantages of the presidency.”

For decades, a common perception has held that a president’s greatest influence is rhetorical. Harvard scholar Richard Neustadt formulated that idea, summarizing it in his famous 1960 phrase: the power to persuade. The bully pulpit, one of the exalted trappings of incumbency, amplifies the president’s policy priorities and shapes public opinion. Or so the assumption went.

In his 2003 book, On Deaf Ears: The Limits of the Bully Pulpit (Yale University Press), Texas A&M political scientist George Edwards III tested the effects of presidential persuasion. From FDR’s fireside chats to the “great communicator” Ronald Reagan to Clinton’s charismatic oratory, Edwards found little evidence that an address to the nation ever increased political support or public esteem.

Yet those same presidents, and most of their counterparts throughout the past century, seldom encountered an impediment to power that they couldn’t overcome. How the executive branch operates in practical terms can be found in the title of Harris School political scientist William G. Howell’s 2003 book, Power without Persuasion: The Politics of Direct Presidential Action (Princeton University Press).

Howell, the Sydney Stein professor in American politics, cites numerous examples of presidential end runs around Congress. Roosevelt issued an executive order permitting the internment of Japanese Americans during World War II. John F. Kennedy used the same mechanism to establish the Peace Corps after Congress denied approval for a similar program three years in a row. Nixon bypassed legislators to create the Environmental Protection Agency as an arm of the executive branch, not an independent regulator. 

From 1920 to 1998, Howell reports, presidents issued an average of almost 90 executive orders per year on substantive policy issues—and they represent just one method of eluding the legislative branch. Presidents also use “executive agreements” with foreign countries to avoid the treaty-ratification process and “national security directives” to conceal information from Congress and the public. “The US Constitution does not explicitly recognize any of these policy vehicles,” Howell writes. “Over the years, presidents have invented them, citing national security or expediency as justification.” That justification, more often than not, receives retroactive ratification from Congress or the courts, if the other branches address the issues at all.

It’s not quite a rubber stamp. Within two months of Truman’s 1952 order for a federal takeover of the nation’s steel plants, to prevent a strike and maintain production for the Korean conflict, the Supreme Court ruled it unconstitutional. Yet the decision in Youngstown v. Sawyer, which Howell calls “perhaps the most important Supreme Court case involving presidential power during the 20th century,” actually lowered the threshold for establishing congressional authorization, effectively expanding executive authority.

In a concurring opinion, Justice Robert Jackson outlined tiers of presidential power. When Congress has prohibited an action, Jackson wrote, executive authority is at its weakest. It’s strongest when an administrative policy has been previously deemed lawful. In between, he added, is a “zone of twilight,” involving subjects that Congress has not yet decided. “The Court has collapsed these last two categories,” Howell writes, turning obscure twilight into clear permission. “Because the absence of congressional action implies consent, the Court upholds the president in both these instances.”

Even an explicit constraint—such as the time limit within the War Powers Resolution—does not necessarily prevent the president from acting. During the Reagan administration, the 1987 Iran-Contra committee’s minority report noted “how far the President’s inherent powers were assumed to have reached when Congress was silent, and even, in some cases, where Congress had prohibited an action.”

Existing law, Posner and Vermeule argue, is “neither here nor there.” What matters is whether the other branches can summon the will to respond after the fact, which traditionally depends more on the political than the legal context. “The overall pattern,” they write, “is that Congress and the courts will tend to fight back only when presidents lack popularity or credibility—the key constraints on executive power.”

Another reason for legislative and judicial reticence to overrule a presidential decision: real-world circumstances change. Once American military power has been unleashed, for example, the other branches must take into account the practical effects of a withdrawal order, not only the abstract question of whether the president violated the law.

During a summer interview in his Law School office, Posner emphasizes that he’s not suggesting the executive branch is “completely unconstrained by legal institutions.” Law and politics overlap. Obama, for example, could have claimed executive authority as commander in chief to end the “Don’t Ask, Don’t Tell” policy on gays in the military—just as Truman ordered desegregation—but instead he let the repeal take a legislative course. In other areas, such as immigration, Obama has acted alone. Politics shapes those choices more than the law, Posner argues, even if they are made in a legal context.

No matter how presidents exercise their authority, their actions foment dissent from the public and from elected officials. Bush and Obama each have been subject to strong rebukes for their counterterrorism policies and their responses to the financial crisis. In the nature of that criticism, though, Posner finds support for his theory that the public generally approves of unilateral executive action.

Obama continued many Bush-era policies, even retaining defense secretary Robert Gates from the previous administration and appointing Timothy Geithner, a key figure in Bush’s economic-crisis management, as treasury secretary. Despite significant policy continuity, the political affiliation of the critics changed. “A lot of people who were criticizing Bush for abusing his power are not criticizing Obama, and a lot of people who were defending Bush are now criticizing Obama,” Posner says. “What that tells me is that we have a constitutional system in which a high level of presidential power is tolerated.”

Perhaps lamented while the other side occupies the White House, but otherwise embraced. “Constitutional norms evolve, and the way you can usually tell is when both parties accept it,” Posner says. “So when the presidency is being traded off by the parties and they act in the same way, that’s evidence that a constitutional norm has developed.”

Posner and Vermeule consider the current norm inevitable, even valuable, writing that “the erosion of checks and balances has promoted national welfare.” A tolerant public, in their judgment, does not imply a compliant public. The political culture encourages skepticism among voters, the authors argue, and the expanding power vested in the presidency only increases scrutiny on the Oval Office occupant. “With discretion comes distrust,” the authors write. The prospect of reelection (or the party’s credibility in a second term) demands attention to public opinion.

If the election is the ultimate constraint, though, does the electorate really have a meaningful voice in the process? Do the broad platforms required to win a major-party nomination truly reflect public priorities? A decentralized government, with more power ceded to local officials, Posner suggests, could offer voters individual candidates who better represent their personal beliefs, but he doesn’t think that’s feasible. “It’s always a question of, what are the superior alternative institutional arrangements?” he says. “When you have a very big country with hundreds of millions of people and all kinds of complex policy issues, [the current system is] basically unavoidable.”

And, he adds, it’s preferable. Most people want government to foster security and prosperity. In the modern world, Posner says, the public has come to believe the “administrative state,” with its powerful executive, best serves those ends. “As technology changed and demographics and the role of the country in the world, it became evident to people that they benefit from having most policy being made at the federal level,” Posner says. “So they were willing to give up that kind of fine-grain choice in return for the benefits that you get from having a very powerful government and a very powerful president.”

To label the president a tyrant for exercising those powers—as opposed to simply disagreeing with a policy choice—strikes Posner as illogical. He takes particular exception to the slippery-slope argument that, for example, targeted killing could be used against average citizens. “They may make bad decisions,” Posner says, acknowledging the validity of condemning such actions, but he refutes the notion that a president’s use of power suggests sinister, antidemocratic intent. “It’s just wild exaggeration to say that the president who does those things is a tyrant.”

Neither the claims to executive authority nor the rhetoric protesting them show signs of abating. In Posner’s opinion, those conflicting points of view reflect the political system’s true checks and balances. The tension inherent in the relationship between the public and the president, he believes, serves democratic ideals as well, if not better, than the constitutional separation of powers.