President Obama’s recent order deferring the deportation of up to 5 million undocumented immigrants has led to enormous controversy. Many, especially on the political right, argue that it undermines the rule of law. The president, they contend, is required to enforce federal law as written, not pick and choose which violators to go after and which to exempt based on policy considerations.

In reality, Obama’s actions were well within the scope of executive authority under the Constitution. In a world where authorities can prosecute only a small fraction of lawbreakers, all presidents inevitably make policy choices about which violations of federal law to prosecute and which to ignore. Such choices are inevitably affected by policy preferences. Obama’s decision to defer deportation is in line with those of past presidents. And if any lawbreakers deserve to benefit from prosecutorial discretion, immigrants fleeing Third World poverty and oppression have a particularly strong case. Moreover, at least under the original meaning of the Constitution, the constitutionality of the immigration laws that Obama has chosen not to enforce in some cases, is itself suspect.

Nonetheless, Obama’s actions do highlight the alarming growth of executive discretion in the modern state. The reach of federal law has grown so vast that no administration can target more than a small percentage of violations, thereby unavoidably giving the president broad discretion. That problem did not begin with Obama, and will not end when he leaves office. It can only be effectively addressed by cutting back on the enormous scope of federal law.

Why Obama’s Use of Executive Discretion Is Not Illegal

Because of the enormous scope of federal criminal law, presidents routinely exercise extraordinarily broad discretion in deciding which violations to prosecute. Far more violators are ignored than punished—or even investigated. To take just one of many examples, for decades federal law enforcement officials have almost never prosecuted the possession and use of marijuana on college campuses, even though such possession is clearly forbidden by the Controlled Substances Act. By doing so, they have let many millions of federal criminals off the hook, including the last three presidents of the United States, each of whom probably used marijuana in their college days. The total is likely far greater than the number exempted from deportation by Obama’s policy.

Article II of the Constitution states that the president must “take Care that the Laws be faithfully executed.” But that requirement does not mean that the president has an absolute duty to prosecute all violations of federal law, or that he cannot choose which ones to pursue based on policy considerations. If it did, virtually every president in the last century or more would be in violation.

Some argue there is a crucial distinction between case-by-case decisions not to prosecute (as with marijuana possession on campus) and a generalized, systematic policy of not doing so in a category of cases. But that distinction makes little sense. After, all, case-by-case decisions are often driven by policy considerations, such as the harm caused by the violation in question and whether federal resources might be better employed elsewhere. Unless case-by-case exemptions are to be completely arbitrary and capricious, they must be guided by at least some general principles, such as the considerations relating to the risks posed by letting the offender go and the moral blameworthiness of his conduct. Once the legitimacy of using such principles to guide prosecutorial discretion is conceded—as it must be—then there is nothing wrong with announcing them in advance and applying them as general rules. If lower-level federal prosecutors and immigration officials can apply such principles, then their superiors—including the president—can issue orders requiring them to do so in a consistent and systematic way. Such systematization helps ensure that like cases are treated alike, as opposed to permitting differential treatment at the whim of individual low-level decision-makers.

At the very least, there is no meaningful difference between a de facto policy of exempting a large category of violations from prosecution (as with marijuana possession on campus) and a more explicit, formal decision to the same effect. If anything, the latter is preferable because it is more transparent and more readily subject to public scrutiny and debate. Because the exemption of campus marijuana users from prosecution has arisen gradually, without any clear formal decision, it has not generated nearly as much public scrutiny and debate as Obama’s order—despite the fact that it lets far more lawbreakers get away with their offenses.

Some critics of formal announcements claim they are worse than unannounced policies because the former encourage future lawbreaking by putting potential offenders on notice that they will not be prosecuted. But college students interested in experimenting with illegal drugs are well aware that there is virtually no chance that they will prosecuted under federal law for possessing marijuana on campus. If anyone is being kept in the dark here, it is the general public beyond the campus walls.

In addition, the people covered by Obama’s order are hardly in the clear. The deferral of their deportation may be reversed at any time, either by Obama himself or a successor. Obama was only partially right when he famously claimed that his order allows those it protects to “come out of the shadows.” They can still be forced back into the shadows at any time.

Obama is far from the first president to exempt large numbers of illegal immigrants from deportation. Past presidents such as Ronald Reagan and George H.W. Bush, have done so as well, including some 1.5 million people in the case of Bush. That does not by itself prove that Obama is acting legally; perhaps Reagan and Bush were undermining the rule of law as well. But it does at least provide an important precedent, especially since few in either party claimed that the prior administrations’ actions were illegal at the time they were done. In this field, Congress itself has delegated wide latitude to the president, which makes the exercise of discretion even less problematic than in many other cases where the law is written in a more categorical way.

Some argue that George H.W. Bush’s decision to exempt some 1.5 million illegal immigrants from deportation in 1990 is different from Obama’s decision because the former exercise of discretion was authorized by Congress in the 1986 Immigration Reform and Control Act, which gave the president authority to preclude deportation in cases where doing so would “assure family unity.” But as the administration’s Office of Legal Counsel points out in its memo defending Obama’s actions, other federal laws give the president authority to forego deportation more generally, including cancellation of removal. In Arizona v. United States (2012) the Supreme Court interpreted existing immigration law as giving the executive branch broad authority to defer deportation for humanitarian reasons. The Court noted that “[a] principal feature of the removal system is the broad discretion exercised by immigration officials” in deciding “whether it makes sense to pursue removal at all,” including by considering “human concerns” such as the fact that many “[u]nauthorized workers” are simply “trying to support their families” rather than committing a “serious crime.”

To the extent that large-scale use of prosecutorial discretion is ever appropriate, it is surely so in the case of helping people whose only violation of the law is fleeing poverty and oppression under terrible Third World governments. Few other offenders have such a compelling moral justification for breaking the law. At the very least, if it is permissible to use executive discretion to forego prosecution of millions of college students who illegally used marijuana on campus, there is a much more compelling case for using it to spare people whose only illegal action was fleeing terrible conditions in their home country, and seeking employment with Americans willing to hire them.

I strongly support the legalization of marijuana and the abolition of the War on Drugs more generally. But illegal immigrants violating the law to escape Third World conditions are considerably more deserving of our compassion than college students violating it to experiment with marijuana for recreational purposes. If exemption from prosecution is acceptable for the latter, the same goes for the former, too.

Dangers of Excessive Discretion and the Overexpansion of Federal Law

There is a danger that wide-ranging presidential use of prosecutorial discretion can result in abuses of power. Indeed, such abuse is almost inevitable in a world where the scope of federal law is so broad that most Americans have probably violated it at one point or another, but only a few are ever likely to be investigated and prosecuted. But that problem existed before Obama’s new policy and the president did not make it any worse than it was before. Long before Obama, presidential administrations unavoidably had to make broad discretionary decisions about which of the many violations of federal law out there were worth prosecuting and which ones were not. And long before Obama, those decisions were influenced by policy and moral considerations.

Some worry that discretion-based defenses of Obama’s order gives the president so much discretion “that no president would ever be in violation” of the Take Care Clause of the Constitution, which requires that he “faithfully” execute federal law. Not so. A president who uses executive power to harass people who haven’t violated any law would be in violation of the duty to “faithfully” execute the law on the books. He would also be in violation if he chose targets for prosecution not based on the severity or importance of the crimes they committed but based on personal animus towards the accused. The president would also violate the Clause if he attempted not only to refrain from prosecuting violators, but to decree that they had not violated the law at all, thereby precluding future presidents from going after the perpetrators as well. Obama has arguably done the latter in the case of his Obamacare waivers; but he did not do it in his immigration executive order.

The president also cannot use his discretion in ways that threaten individual rights protected by the Constitution. For example, he cannot choose which offenders to prosecute based on the race, sex, religion, or political views of the potential defendants. The IRS’ selective targeting of conservative and Tea Party-aligned groups was illegal because they were targeted based on their exercise of First Amendment rights.