The Volokh Conspiracy

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Reaching Equilibrium: How Do Criminal Law Conventions Develop?


Justice Scalia's celebrated dissent in Morrison v. Olson, which argued that the independent counsel statute was unconstitutional, contains two important themes. The first concerned separation of powers and explained why Congress had unconstitutionally removed an officer exercising purely executive power from the supervision of the President. But Part V of the opinion heads in a different direction: checks and balances. Quoting Justice Jackson, Justice Scalia explained, "With the law books filled with a great assortment of crimes, a prosecutor stands a fair chance of finding at least a technical violation of some act on the part of almost anyone." To curtail prosecutors' expansive formal legal power, Justice Scalia understood that "the primary check against prosecutorial abuse is a political one."

While statutory criminal laws may be broad, they are narrowed by unwritten criminal law conventions. And criminal law conventions develop because executive officials face political sanctions for violating them.

Observe, for example, the dispute over federal enforcement of marijuana laws. Between 2009 and 2013, the Department of Justice instructed U.S. Attorneys not to prosecute those growing and using marijuana lawfully under state law. At first, the guidance was applied to medical marijuana, but the Department later expanded it to cover recreational marijuana in states that had legalized it. Five years later, President Trump was in office. His Attorney General, Jeff Sessions, opposed marijuana legalization and rescinded the memo. The political backlash was swift. Senator Cory Gardner—a Republican from Colorado, which had legalized recreational marijuana—responded by blocking the confirmation of about twenty Department of Justice nominees. With a member of his own party refusing to confirm nominees, President Trump promised (despite his duty to "faithfully execute the laws") that the Department of Justice would not interfere with Colorado's marijuana industry. Thus, even though Sen. Gardner could not successfully get Congress to amend or repeal the federal law on marijuana, he attained de facto decriminalization by raising the political price of enforcement beyond what the executive branch was willing to pay.

Prosecutors face significant pressures from a multitude of directions. Legislatures may pass broad and vague criminal laws, which empower prosecutors. But then legislatures curb that power by controlling enforcement agencies and threatening legal reform if prosecutors become overzealous. Legislatures also strip power from prosecutors who underenforce the law. Larry Krasner, the Philadelphia District Attorney, has come under severe criticism for his proposed leniency in cases involving violent crimes and gun crimes. The Pennsylvania legislature responded by giving the state Attorney General concurrent jurisdiction to prosecute certain gun crimes in Philadelphia, thereby weakening Krasner's ability to set criminal justice policy in the city.

Many prosecutors face electoral pressures. In some jurisdictions, this makes it difficult for prosecutors to be excessively lenient. More recently, however, excessive enforcement has become politically toxic, with many cities electing "progressive prosecutors." Federal prosecutors are appointed, not elected. But their conduct affects the president's political fortunes, and many U.S. Attorneys harbor ambitions for higher political office. So they are often responsive to voters' concerns.

Juries make it difficult for prosecutors to bring cases against sympathetic defendants or defendants who, although they may have technically breached some law, have not violated community norms. Faced with improperly brought cases, jurors may nullify. And even if they do not nullify, jurors may review the evidence in the light most favorable to a sympathetic defendant. Although few cases today go to juries, enforcement decisions take place in the shadow of the jury. The threat that the defendant may take the case before the jury influences and disciplines how prosecutors act. (See, for example, Anna Offit's article Prosecuting in the Shadow of the Jury.)

Judges have a variety of tools to combat prosecutorial abuse. Some are legal. Faced with vague or overbroad laws, judges may construe them to contain strict mens rea requirements, by narrowing the actus reus, or by striking them down as unconstitutional. A few jurisdictions have adopted Section 2.12 of the Model Penal Code, which gives judges power to dismiss "de minimis infractions." Appellate judges may also be more apt to reverse convictions of sympathetic defendants for trial errors that, for less sympathetic defendants, may be written off as harmless. And judges have soft-power tools. They can encourage prosecutors to drop charges or plead them out at reduced sentences. In many cases, a judge may lack the legal power to stop a determined prosecutor from seeking a maximum sentence. But prosecutors are repeat players who are incentivized not to anger judges before whom they appear.

Finally, the expansion of federal criminal law paradoxically may curb some prosecutorial abuses. Duplicative federal criminalization can make it difficult for local officials to be too lenient. Krasner's leniency led the Philadelphia U.S. Attorney to indict some violent-crime defendants under harsher federal law. Excessive harshness or leniency can also trigger "uncooperative federalism" among federal and state agencies. Federal and state law enforcement are interdependent. State governments have far more police and prosecutors, while the federal government has sophisticated investigative resources and provides grants to state and local governments. Prosecutors who defy norms may strain this relationship.

Given the variety of checks on prosecutorial power, one question that emerges with unwritten conventions is whether the conventions are national or local in nature. I think there are some of both. Unwritten English law recognized both "general customs," which Blackstone called "the common law, properly so called" and "particular customs" which Blackstone described as unwritten laws that "affect[ed] only the inhabitants of particular districts." In our federal system, I think criminal law conventions have a similar structure. Some conventions are national—e.g., the decriminalization of consensual sex offenses. Others may be local, such as cities that widely tolerate some personal use of recreational drugs or refuse to enforce certain gun crimes.

Having multiple layers of customs promotes development in the law. As local governments experiment with new norms, some local customs (e.g., drug decriminalization) may spread nationally. In other cases, national norms can override pernicious local customs. For example, in the 1960s, the federal government, faced with local legal systems in the South that widely tolerated violence against African Americans, began prosecuting some racially motivated violence under federal civil rights laws. Duplicative federal-state criminalization, thus, provided a countermeasure against local customs that left African Americans vulnerable to violence by underenforcing the law.

In summary, indirect sanctions discipline prosecutors and curb the effective scope of their discretion. To restate a point that I made in my last post, I do not think that current criminal law conventions solve all that ails our criminal justice system. Obviously, it does not. My final post tomorrow will tackle some of those issues. But the existence of considerable constraints on prosecutorial discretion does much to mitigate the potential harms of our imperfect statutory criminal law.