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There is a common refrain in U.S. legal scholarship that an assertive exercise of judicial power in matters of national security jeopardizes established institutional arrangements. In war and national security, the executive takes the lead, with some legislative oversight. The legislative branch is constitutionally empowered and institutionally suited to check executive excesses in war and national security. The argument tends to go something like this: robust judicial review that thoroughly engages with the substance of executive power and decision making in national security is likely to impose unworkable limits on executive power, thereby compromising security and legitimate exercises of executive power. What is more, when courts take the reins, the legislature is pushed out, or loses the incentive to act and provide political checks on executive power. Judicial engagement leads to legislative disengagement. Political checks, provided by the legislative branch, are constitutionally and institutionally appropriate for this context, where our knowledge of what is possible, both practically and legally, is evolving constantly and rapidly. Where the law needs to be responsive to the demands of unstable and varying circumstances, reliance on the judicial branch—the institution least able to change its rules quickly in the face of multi-dimensional problems of security and intelligence—is misguided and dangerous. This line of reasoning is concerned with the consequences of judicial activity and willing to forgo searching scrutiny by appealing to and relying on legislative checks. It has come to dominate U.S. jurisprudence. Even scholars arguing for a robust application of judicial review and an extension of substantive legal limits and protections in the national security arena place little emphasis on institutional interplay.
This Article argues for a more nuanced understanding of institutional competence and interplay in national security. A more nuanced understanding would ensure overlap of institutional authorities is not confused with conflation of those authorities. An either/or approach to checking executive power and dominance in national security, rooted in either extension of judicial supremacy or popular constitutionalism, fails to adequately consider and value institutional interplay. There is value in substantive judicial review of executive decision-making in national security beyond the judicial protection of individual rights. If judicial review can prompt more substantive legislative engagement, then there is a systemic value to substantive judicial engagement.
The focus in this Article is two-fold. First, this Article addresses the role of the legislature and the importance of legislative engagement for effective checks on executive discretion and the proper functioning of separation of powers. Second, it consider how judicial review can prompt legislative activity. In the national security arena, the dangers of judicial activity, understood as judicial activism, are often emphasized without adequate acknowledgement of the fact that judicial avoidance can be equally activist and impact the political process. Judicial timidity can facilitate legislative disengagement, especially when the challenged action arises in a constitutionally fraught area where the impacted population has no political voice. Ultimately, such judicial and legislative disengagement significantly compromises the proper functioning of the separation of powers.
This Article focuses on U.S. and U.K. experiences in order to challenge, through specific examples, the stated or assumed claim that judicial review of matters of national security is undesirable and inadvisable. Judicial review can prompt better legislative oversight of executive action. U.S. and U.K. experiences present two different examples of judicial and legislative behavior. Facing a similar challenge, and relying on similar constitutional, institutional, and normative principles, the courts in these jurisdictions made different choices. Correspondingly, the legislatures in these two jurisdictions made different choices. In the United States, where the courts remained inactive/deferential, the legislature made no changes to the legal framework authorizing executive power. As this Article will show, U.S. courts deferred, adopting substantive, procedural, and evidentiary standards that rendered judicial review little more than a rubber stamp of executive policy. In turn, Congress could, and did, fail to set any real standards for executive detention authority. In contrast, in the United Kingdom, where the courts exercised some scrutiny, pointing out constitutional flaws, the legislature made some attempts to remedy those faults and make more constitutionally conscious choices. Given the fundamental nature of the right at stake, the right to liberty and security, U.K. courts understood themselves to be constitutionally and institutionally responsible for exercising real scrutiny of executive judgement. In their case, a proper exercise of judicial power prompted legislative engagement and produced a more effective functioning of the separation of powers, one in which the legislature engaged with the substantive standards and issues at stake.
First, this Article will lay out the initial legislative authorization of executive power in each jurisdiction and the judicial scrutiny that followed. Then, it will explain why focusing on these jurisdictions is fitting and how the difference in judicial review presents an opportunity to examine the relationship between judicial review and subsequent legislative engagement. The Article will turn to the question of legislative development of the legal framework and what that development, or lack thereof, means for separation of powers in national security. As the examination of these two jurisdictions will show, the assumption that judicial activity is dangerous to proper functioning of separation of powers, in national security, is faulty, rooted in broad generalizations about institutional roles and a simplistic understanding of institutional dynamics.
[*] Clinical Faculty and Staff Attorney, UIC John Marshall Law School, International Human Rights Clinic. Former International Human Rights Fellow and Lecturer-in-Law, University of Chicago Law School. PhD 2017, University of Cambridge; J.D. 2011, Notre Dame Law School. For constructive comments and helpful conversations, I would like to thank Aziz Huq, Claudia Flores, Mary Ellen O’Connell, Mark Elliott, Vicki Jackson, and participants of the 2018 ICON Conference panel and University of Chicago Law School Junior Scholars Colloquium. I am very grateful to Philip Chertoff and other editors at the Harvard National Security Journal for their careful and painstaking work on this article.
 See Neal Katyal, Stochastic Constraint, 126 Harv. L. Rev. 990, 1002 (2013) (reviewing Jack Goldsmith, Power and Constraint: The Accountable Presidency After 9/11 (2012)) (“Because of their aforementioned competence limitations, they will often stay on the sidelines of national security disputes. But when they do get involved, they may overreact in ways that could last for generations due to stare decisis.”); Robert M. Chesney, Who May Be Held? Military Detention Through the Habeas Lens, 52 B.C. L. Rev. 769, 856 (2011) (“[L]egislative rulemaking as a general proposition is more easily revisited than rules derived through the habeas process . . . Judicially crafted rules are not so readily altered, however.”); Mark V. Tushnet, Policy Distortion and Democratic Debilitation: Comparative Illumination of the Countermajoritarian Difficulty, 94 Mich. L. Rev. 245, 245; Similar institutional claims can be found in U.K. jurisprudence and scholarship. Secretary of State for the Home Department v. Rehman  1 AC 153  (Hoffmann LJ) (“I wrote this speech some three months before the recent events in New York and Washington. They are a reminder that in matters of national security, the cost of failure can be high. This seems to me to underline the need for the judicial arm of government to respect the decisions of ministers of the Crown on the question of whether support for terrorist activities in a foreign country constitutes a threat to national security. It is not only that the executive has access to special information and expertise in these matters. It is also that such decisions, with serious potential results for the community, require a legitimacy which can be conferred only by entrusting them to persons responsible to the community through the democratic process.”); Lord Hoffmann, The COMBAR Lecture 2001: Separation of Powers, 7 Jud. Rev. 137, 144 (2002) (“[A] degree of political awareness from judges, the ability to identify cases in which behind the formal structure of legal reasoning with which judges are so familiar, there lie questions of policy which are more appropriately decided by the democratically elected organs of the state. And it requires a degree of restraint on the part of the judges; a willingness to stand back from the thickets of the law and accept that judges are not appointed to set the world to rights.”).
 See, e.g., Curtis A. Bradley & Jack L. Goldsmith, Congressional Authorization and the War on Terrorism, 118 Harv. L Rev. 2047, 2051-52, 2086 (2005); John C. Yoo, Judicial Review and the War on Terrorism, 72 Geo. Wash. L. Rev. 427, 440 (2003); Robert Bork & David Rivkin Jr., A War the Courts Shouldn’t Manage, Wash. Post A17 (Jan. 21, 2005).
 See Mark V. Tushnet, Controlling Executive Power in the War on Terrorism, 118 Harv. L. Rev. 2673, 2680 (2005) (“Further, if courts purport to police the policymaking process but actually supervise it with an extremely loose hand, the negative case asserts that the judicial-review mechanism might worsen the political branches’ performance because their members might mistakenly believe that the courts will bail the people out of whatever trouble the political branches make.”); see also Cass R. Sunstein, Administrative Law Goes to War, 118 Harv. L. Rev. 2663, 2666 (2005) (“[T]he AUMF is best taken, by its very nature, as an implicit delegation to the President to resolve ambiguities as he (reasonably) sees fit. This position tracks Congress’s likely expectations, to the extent that they exist; it also imposes exactly the right incentives on Congress, by requiring it to limit the President’s authority through plain text if that is what it wishes to do.”).
 See, e.g., Al-Bihani v. Obama, 590 F.3d 866, 882 (D.C. Cir. 2010) (Brown, J., concurring) (“[T]he circumstances that frustrate the judicial process are the same ones that make this situation particularly ripe for Congress to intervene pursuant to its policy expertise, democratic legitimacy, and oath to uphold and defend the Constitution. These cases present hard questions and hard choices, ones best faced directly.”).
 See Korematsu v. United States, 323 U.S. 214, 224 (1944) (Frankfurter, J., concurring) (“The provisions of the Constitution which confer on the Congress and the President powers to enable this country to wage war are as much part of the Constitution as provisions looking to a nation at peace.”); Youngstown Sheet & Tube Co. v. Sawyer, 343 U.S. 579, 603–610, 635 (1952); Al-Bihani, 590 F.3d at 871 (deferring to Congress and the President to establish the substantive laws of war that inform detention authority); Al-Aulaqi v. Panetta, 35 F.Supp.3d 56, 78–79 (D.D.C. 2014); Ziglar v. Abbasi, 137 S.Ct. 1843, 1860 (2017); Trump v. Hawaii, 138 S.Ct. 2392, 2408–2410 (2018).
 See David Cole, Rights Over Borders: Transnational Constitutionalism and Guantanamo Bay, Cato Sup. Ct. Rev. 2007–2008, at 47, 56–61; see generally, David Dyzenhaus, The Constitution of Law: Legality in a Time of Emergency (2006) (focusing on substantive bill of rights protections rather than institutional benefits); see generally Ryan Goodman and Derek Jinks, Replies to Congressional Authorization: International Law, U.S. War Powers, and the Global War on Terrorism, 118 Harv. L Rev. 2653 (2005) (focusing on the substantive limits provided by Laws of Armed Conflict on executive power authorized through congressional authorization, rather than the institutional benefits of robust judicial review).
 For a discussion of judicial supremacy and popular constitutionalism, see generally Richard H. Fallon, Jr., Judicial Supremacy, Departmentalism, and the Rule of Law in a Populist Age, 96 Tex. L. Rev. (2018).
 See Tushnet, supra note 1, at 246–7. See generally J Mitchell Pickerill, Constitutional Deliberation in Congress: The Impact of Judicial Review in a Separated System (2004).
 Stephen Sedley, The Sound of Silence: Constitutional Law without a Constitution 110 L.Q. Rev. 270, 284 (1994).
 See Oona A. Hathaway, Presidential Power over International Law: Restoring the Balance, 119 Yale L.J. 140, 144 (2009) (“Once a duty shared by Congress and the President, the task of concluding international agreements has come to be borne almost entirely by the President alone.”); see also Curtis A. Bradley and Jack L. Goldsmith, Presidential Control over International Law, 131 Harv. L. Rev. 1201, 1272–9 (2018).
 See European Convention for the Protection of Human Rights and Fundamental Freedoms art. 5, Nov. 4, 1950, 213 U.N.T.S. 222 [hereinafter Convention].