Intent crimes are often categorized as either general or specific. General intent crimes require the state to prove that the defendant “purposefully or voluntarily performed the wrongful act” when seeking a conviction.[12] A specific intent crime requires a “particular criminal intent beyond the act done” — in other words, committing an act for a particular criminal purpose.[13] For example, burglary traditionally requires breaking and entering with the intent to steal.

A third category of crime is called strict-liability crimes. Strict-liability crimes require no mens rea — a criminal penalty can be imposed regardless of the intent of the actor. Statutory rape, for example, is penalized regardless of a defendant’s knowledge of the victim’s age.[14] As the Michigan Supreme Court has explained:

For a strict-liability crime, the people need only prove that the act was performed regardless of what the actor knew or did not know. On this basis, the distinction between a strict-liability crime and a general-intent crime is that, for a general-intent crime, the people must prove that the defendant purposefully or voluntarily performed the wrongful act, whereas, for a strict-liability crime, the people merely need to prove that the defendant performed the wrongful act, irrespective of whether he intended to perform it.[15]

The regulatory response to growth of industrialization and urbanization in the late 19th century introduced a new form of strict-liability crimes, commonly known as “public welfare” offenses, which legislatures began enacting under their police power to promote social order.[*] New industrial advances, the congestion of cities and wide distribution of goods all posed new potential dangers to the public. Public welfare regulations were intended to “heighten the duties of those in control of particular industries, trades, properties or activities that affect public health, safety or welfare.”[16] These laws were regulatory in nature, intended to prevent public harms that could occur from neglecting a duty of care.

Over time, legislatures used the criminal code, with its power of prosecution and sanctions, for regulatory purposes. In a seminal article written in 1933, Harvard law professor Francis Sayre categorized typical public welfare offenses: the improper sale of alcohol, sale of adulterated food and drugs or misbranded articles, criminal (or “public”) nuisances, and violations of traffic, motor vehicle and other laws concerning public safety and public health.[17] Early public welfare cases in Michigan penalized the sale of mustard adulterated with turmeric and opening a saloon on a Sunday.[18]

Significantly, public welfare offenses omit the requirement to establish blameworthiness for a criminal conviction; liability can be imposed irrespective of the actor’s intent. Legal commentators have theorized that public welfare offenses were favored by lawmakers because of the ease of conviction, as requiring proof of mens rea places a greater burden on the prosecution.[19] Public welfare laws often regulated behavior that would, but for the prohibition, be considered innocent conduct; a stop sign at a deserted intersection does not represent a moral imperative.

Today, it is quite common for legislatures and Congress to be silent on intent, creating the inference that strict liability is to be imposed. A 2010 joint report by The Heritage Foundation and the National Association of Criminal Defense Lawyers examined legislation that would create new nonviolent criminal offenses proposed by the 109th U.S. Congress in 2005 and 2006. The authors determined that 57 percent of the proposed offenses contained inadequate mens rea requirements, and 64 percent of the proposals enacted into law were lacking mens rea provisions.[20]

[*]  For more on the origins of public welfare offenses, see: Catherine L. Carpenter, “On Statutory Rape, Strict Liability, and the Public Welfare Offense Model,” American University Law Review 53, no. 2 (2003): 313–391, accessed Nov. 20, 2013,; Richard G. Singer, “The Resurgence of Mens Rea: The Rise and Fall of Strict Criminal Liability,” Boston College Law Review 30, no. 2 (Mar. 1, 1989): 337–408, accessed Nov. 20, 2013,