Article II of the U.S. Constitution states that "executive power shall be vested in a President of the United States," and "he shall take care that the laws be faithfully executed." While Congress is understood to be the primary institution in the policy-making process, ambiguity about the meaning of "executive power" and "faithfully execute" has opened the door for many influential policy decisions to be made by presidents acting unilaterally. The internment of Japanese Americans during World War II by President Franklin Delano Roosevelt (Executive Order 9066), President Harry Truman's desegregation of the military (Executive Order 9981), the creation of the Peace Corps by President John F. Kennedy (Executive Order 10924), and the creation of the White House Office of Faith-Based and Community Initiatives by President George W. Bush (Executive Order 13199) are examples of consequential unilateral policy-making actions taken by presidents.
Although legal scholars have long examined the constitutionality of executive orders and other unilateral actions, it is only within the last two decades that political scientists have paid significant attention to unilateral uses of presidential power. In explaining why executive orders have gone understudied, Mayer notes, "This neglect of executive orders, and the downplaying of their importance is largely attributable to the tendency among scholars of the presidency to concentrate on 'questions about the personalities, power, and leadership of specific presidents'" (Mayer 1999, 447). While scholars bemoan the focus on individuals in the study of the presidency, there has been no systematic study of how factors inherent to individual presidents influence their propensities to issue executive orders. In studying the use of unilateral actions, political scientists have focused exclusively on the influence of contextual factors including the partisan makeup of the legislature, the stage in a president's term, whether the country is at war, and the type and significance of the issues that executive orders address. Despite the obvious expectation that some presidents should be more inherently disposed to take power into their own hands, this hypothesis has never been systematically tested. Thus, this study is the first to examine the influence of presidents' personalities on the frequency with which they use executive orders to carry out their agendas.
In the sections that follow, we review the literature on executive orders, taking note of the ways in which instruments of unilateral action relate to conceptions of presidential power. After describing the Big Five model, the dominant paradigm in trait psychology, we propose that several traits, namely, those that are related to risk taking and the desire to carry out goals, should influence the frequency with which presidents issue different types of executive orders. The results of our models provide support for the argument that presidents' personalities matter, as does the institutional context within which presidents act.
Unilateral Action and Presidential Power
According to Neustadt's (1991 ) theory of presidential power, the persuasive president will carry out his objectives by using the status and authority of his office to augment his inherent personality (what Neustadt calls the president's "logic and charm"). Moe and Howell summarize the argument: "The key to strong presidential leadership, he [Neustadt] argued, lies not in formal power, but in the skills, temperament, and experience of the man occupying the office and his ability to put these personal qualities to use in enhancing his own reputation and prestige. The foundation of presidential power is ultimately personal" (1999, 850). While Neustadt's work remains seminal to presidency studies, scholarship in the field has moved away from the personal presidency to instead focus on the institutional presidency (Moe 1993).
The personal presidency perspective overlooks the growth and development of the presidency as an institution, evidenced by increases in staff, budget, and powers delegated by Congress (Howell 2003, 10). It is through the lens of the institutional presidency that scholars have developed a rich literature on unilateral executive action. Moe and Howell's (1999) institutional theory of unilateral action argues that the prevalence and importance of unilateral actions derive from the fact that they are not formally specified in the Constitution. Faced with outstanding demands for policy change, the president has the ability and incentive to move first and act alone to carry out his agenda. In this sense unilateral action is the "virtual antithesis of persuasion ... presidents simply set public policy and dare others to counter"(Howell 2005,421).
While unilateral actions free the president from having to persuade others that what the White House wants of them is what they should want for themselves, it does not mean that the president is without constraints from other institutions. Using unilateral power requires the president to consider the costs of having the action overturned by Congress or the courts. The president must be strategic; he may want to take unilateral action to circumvent a hostile Congress but will be reluctant to take action that Congress or the courts are likely to overturn for fear of damaging his "professional reputation" and prospective power (Deering and Maltzman 1999; Moe and Howell 1999; Neustadt 1991). Even when it is unlikely that their orders will be overturned, presidents run the risk of creating opposition that will undermine other aspects of their agenda (Howell and Kriner 2008; Moe and Howell 1999).
We should not expect presidents to be equally adept at anticipating the reactions of the other institutions of government, or that they will choose to adjust their actions in the same way. Some may prefer to lead by command, despite the risks of creating conflict with the other branches and having their orders overturned, in exchange for the expediency of carrying out their policy objectives. Individual differences, most notably their personality traits, will influence how presidents perceive their power vis-a-vis other branches.
Studies of Executive Orders
Howell (2003) posits two sets of circumstances under which presidents are likely to issue executive orders, both of which hinge on the ability of Congress to constrain the president. In the first case, the president issues an executive order that will lead to moderate policy in order to preempt Congress from passing sweeping policy change. The second and more common case is when Congress is unwilling or unable to pass the president's chosen policy. To break the gridlock, the president creates policy by circumventing Congress. The notion that presidents use executive orders to circumvent hostile Congresses is referred to as the strategic model and was once accepted as conventional wisdom; however, the hypothesis has received mixed empirical support. The literature focuses on several conditions expected to be associated with legislative gridlock: divided government, the presence of large ideological distance between the president and Congress, and the presence of small, internally divided parties in Congress.
The first tenet of the strategic model is that divided government should be associated with increased use of executive orders. However, most studies that identify a significant divided government effect find that presidents issue fewer executive orders during divided government, not more (e.g., Howell 2003, 2005; Howell and Mayer 2005; Krause and Cohen 1997; Mayer 2001; Warber 2006; Young 2013). Others do not find evidence that divided government matters either way (e.g., Deering and Maltzman 1999; Marshall and Pacelle 2005). These results suggest that, when presidents face fewer constraints from Congress, they take advantage of the situation to lead alone (Howell 2003) and that they use executive orders not only to circumvent and preempt Congress, but also to reinforce successful legislation (Krause and Cohen 1997). On the other hand, Fine and Warber (2012) find that divided government results in more frequent use of executive orders when the president's party controls fewer seats in the House of Representatives.
Divided government is only one indicator of potential congressional hostility. Deering and Maltzman (1999) find support for the hypothesis that presidents are more likely to issue executive orders when they are ideologically distant from Congress. Fine and Warber (2012) also find this to be the case when it comes to major policy executive orders, but not total executive order activity. Howell (2003, 2005) and Young (2013) conclude that, when congressional majorities are small, presidents issue more significant orders.
Studies of executive orders have examined contextual factors beyond the composition of Congress and its relationship to the occupant of the Oval Office. Mayer and Price (2002), for instance, propose that presidential approval should be inversely related to the number of executive orders issued. They reason that, if Neustadt's argument that presidents are dependent upon public prestige to maintain their power is correct, then those who "can marshal public prestige need not resort to this version of 'command' to achieve desired outcomes" (378). (1) The results of their study, as well as others (e.g., Deering and Maltzman 1999; Mayer 1999) bear out these expectations.
While individual level-factors inherent to the president have not been systematically studied, scholars have examined the effect of several contextual variables directly related to the particularities of a presidency. For instance, they have studied the influence of a president's stage in office on the frequency of executive order usage. Mayer (2001; see also Mayer and Price 2002) finds that presidents issue nearly twice as many executive orders...