President Obama’s executive actions on immigration are now before the Supreme Court. Although our immigration system is broken, Congress’s failure to fix it doesn’t give the president the power to institute reforms himself. Yet through the Deferred Action for Parents of Americans and Lawful Permanent Residents program (DAPA), the executive branch has given temporary legal status to more than four million illegal migrants, entitling them to work authorizations and other benefits. DAPA amounts to a deliberate effort to bypass Congress and conflicts with five decades of congressional immigration policy. Perhaps most importantly, it violates the separation of powers and is thus unconstitutional. In what has become routine under this administration, 26 states sued the federal government in response to this executive action. In February 2015, a federal district court blocked DAPA from going into effect, finding that the executive branch did not follow the proper administrative procedures before implementing what is effectively a substantive change in established immigration law. The government appealed this judgment to the U.S. Court of Appeals for the Fifth Circuit, which affirmed the temporary injunction. When the Supreme Court decided to hear this case, it asked the parties to address four issues: (1) whether at least one state has standing to sue when DAPA will cost the state millions; (2) whether DAPA is subject to the Administrative Procedure Act’s technical procedural requirements for making regulatory changes; (3) whether DAPA violates the law as enacted by Congress in the Immigration and Naturalization Act and related statutes; and (4) whether the president’s actions violate his constitutional duty to “take care that the laws be faithfully executed.” Cato’s brief, primarily authored by Prof. Josh Blackman and joined by Profs. Randy Barnett and Jeremy Rabkin, addresses the fourth issue, the Take Care Clause of Article II. This clause originated in response to British monarchs’ practice of suspending the law, crossing the line between executive and legislative functions. As the Framers knew well, in the wake of the Glorious Revolution, the English Bill of Rights eliminated “the pretended power of suspending . . . or the execution of laws by regal authority.” Nevertheless, King George III routinely refused his assent to laws enacted by colonial legislatures, insisting that they contain a provision authorizing the king to suspend their authority. This expansion of executive power yielded the first two grievances in the Declaration of Independence. Analysis of the text of the Take Care Clause and Supreme Court precedent reveals that the president’s duty to enforce the law entails four distinct but interconnected components: the duty is mandatory and not discretionary; the president must act with care; the president must execute the law, not author new legislation; and the president must make a faithful effort to enforce the content of the laws Congress passes. DAPA amounts to a legislative act and is not a good faith or careful attempt to execute the law. Cato urges the Supreme Court to affirm the judgment of the Fifth Circuit. Alternatively, the Court should dismiss the writ of certiorari—what the “decision to decide” is called—as improvidently granted, which would leave the injunction of DAPA in place but set no precedent for the future. It’s likely that the next president will either expand or rescind DAPA, thus either transforming the case into something new for the lower courts to evaluate or mooting it altogether.