Malum prohibitum is a Latin phrase used in Anglo-American criminal law to describe an act that is wrongful only because a legislative body has declared it unlawful, as distinguished from malum in se, an act that is wrongful in itself. On The Bob Zadek Show the distinction recurs as the analytical hinge for arguments about overcriminalization, prison spending and the moral authority of the criminal law. Host Bob Zadek, an attorney, introduced the pairing as a piece of legal vocabulary he uses when he occasionally resorts to Latin, and guests across four episodes adopted it as their own framing.
The distinction stated
Zadek’s fullest statement of the dichotomy came in a 2011 episode on prison costs. He translated malum as bad, and defined malum in se as acts that are bad per se — rape, robbery and murder — which every culture would consider crimes and from which people are to be protected. Malum prohibitum, by contrast, covers acts he described as neutral, not necessarily bad, which laws make bad. His examples included insider trading and drug use, and he said the prison system is loaded up with people who commit acts that have been decided ought to be bad for transient social reasons, so that the public ends up paying for incarceration, free meals and free medical care with no benefit to society Crime Down: Prison Costs Up (2011).
Alex Nowrasteh, in a 2015 episode on immigration, grounded the same distinction in an Enlightenment idea that laws need to be discovered, not made. He said the laws most people respect — murder and theft — are similar across all human civilization and time and are discovered, whereas laws restricting drug use, firearm ownership or immigration are made, created out of whole cloth by legislators, bureaucrats and activists with no account of how humans actually view these things. Zadek restated the dichotomy in reply, calling malum prohibitum wrong only because somebody in some legislative body decided an otherwise innocent or lawful act should be made unlawful, and describing such laws as unnatural impositions and an attempt to legislate morality. Nowrasteh agreed, adding that most of the problems with illegality and most of the reason people do not respect the law as much as they used to arise because almost all laws are now of this type, where there is no victim Immigration Nation: Nowrasteh Sets it Straight Again (2015).
The War on Drugs as the paradigm case
Dr. Rick Doblin, in a 2016 episode on MAPS and the War on Drugs, supplied the historical case study. He said marijuana had been criminalized in 1937 through the Tax Act and taken out of the pharmacopoeia in 1942, in part through Harry Anslinger and prohibition agents who, a few years after the end of alcohol prohibition, were looking around for something else to criminalize; he said the drug was mostly used by Mexicans and black jazz musicians and became a convenient target. Doblin also said the American Medical Association argued against criminalization in Congress, testifying that marijuana had medical uses and that the evidence of abuse was massively exaggerated, and that its testimony was completely ignored Dr. Rick Doblin on MAPS and the War on Drugs (2016).
Zadek used the episode to state the distinction again, defining malum prohibitum as wrong only because somebody declared it to be wrong by statute, not because it violates any group of people’s moral code, and calling the possession and use of marijuana a perfect example. He said a criminal statute should reflect the morality of society and should not criminalize otherwise non-criminal acts. Doblin extended the argument to felony disenfranchisement, saying the drug war has been used to disenfranchise enormous numbers of voters and that in many states felons are prohibited from voting even after serving their time, and he cited The New Jim Crow as a book about how the drug war is used to suppress voters. Zadek also traced the racist roots of early drug laws, quoting a Journal of the American Medical Association editorial claiming that Negroes in the South were reported as addicted to cocaine sniffing, a blue-ribbon panel’s statement that if the Chinaman cannot get along without his dope we can get along without him, and a New York Times article describing Negro cocaine fiends as a new Southern menace Dr. Rick Doblin on MAPS and the War on Drugs (2016).
Mens rea and the explosion of regulatory offenses
Robert Alt of the Buckeye Institute, in a 2017 episode on federalism, connected malum prohibitum to the guilty-mind requirement. He said that at both the state and federal level the number of crimes on the books carrying criminal penalties has absolutely exploded while protections for the accused — requirements that a person have some form of guilty mind or criminal intent — have been extraordinarily weakened. He described a joint report with the National Association of Criminal Defense Lawyers, produced while he was at the Heritage Foundation working for Ed Meese, which found 446 proposed non-violent criminal offenses in a single Congress, 57% of them with an inadequate criminal intent requirement, and 64% of the laws actually enacted containing inadequate mens rea requirements Robert Alt of the Buckeye Institute: Power to the States (2017).
Zadek framed the stakes: if a statute criminalizes an activity that is not inherently bad, a person performing an act that seems innocent to them has no way to know they are breaking the law, and the very purpose of criminal law is defeated. Alt offered the desert-island test he used when teaching criminal law — a person dropped into an unknown society would know not to steal or kill, but would not know whether form XJ6 must be filed on the 12th of the month in triplicate, though that latter thing could in fact be a crime. He cited an American Bar Association task force from 1998 that concluded the body of federal criminal law is so large that there is no conveniently accessible complete list of the crimes; the task force catalogued well over 3,000 crimes, and by 2007 the number had jumped to over 4,450, increasing at a rate of about 56 and a half crimes per year. He described Ohio’s response: if the legislature creates a new crime in a bill without a criminal intent requirement, the crime is void — what he called the strongest medicine of anyplace in the country, because it holds the legislature accountable. He illustrated the danger with a Florida example in which drug possession laws were modified to make it easier to prosecute traffickers and the criminal intent requirement was eliminated, so that a renter who unknowingly drove a car with narcotics packed in the spare tire could be convicted because he constructively possessed the narcotics Robert Alt of the Buckeye Institute: Power to the States (2017).
Across episodes
The distinction is argued in all four episodes, and the treatment develops in emphasis rather than in substance. Zadek states it himself in 2011 and again in 2015 and 2016, each time with the same definition and the same core examples; Nowrasteh in 2015 supplies the discovered-versus-made framing, Doblin in 2016 supplies the political and racial history of drug prohibition, and Alt in 2017 shifts the discussion from the definition of malum prohibitum to the procedural safeguard of mens rea and to concrete counts of federal crimes. No guest contradicts another, and no episode revisits an earlier claim.
What the sources do not cover
The excerpts do not state the origins or first use of the phrase malum prohibitum, nor any judicial decision construing it. They do not give the text, title or enactment date of the marijuana Tax Act Doblin mentions, nor the name of the Shafer Commission’s formal report. The Florida drug-possession change and the Ohio criminal-intent provision are described without bill numbers or citations, and the excerpts break off before several speakers finish their points.