Section 1.3: The Criminal Act

Fundamentals of Criminal Law by Adam J. McKee

To spark debate in the classroom, I often make controversial and inflammatory statements to which I expect at least someone to make an objection.  With this strategy in mind, I offered a definition of a crime to my students:  “A crime is a rule of law prohibiting an activity that a group of elite, rich, old, white men don’t want you to do.”  Much to my surprise, the strategy backfired. Most of my college students agreed with that position, and I had to take the other side of the debate to keep the class moving.  

Whatever you think of that actual premise, it does point out the fact that crimes, when taken as a whole, have very little in common.  Most mala in se offenses are universally criminal.  Murder, rape, robbery, arson, and burglary are nowhere acceptable (except for places where the rule of law does not prevail).  

Other crimes are held in contempt by a majority of people, and the continued criminalization of some acts undermines the public respect for the laws (and, sadly, the officers that duty-bound to enforce them).  The most publicized example as I write this is the cannabis legalization debate. Vestiges of puritanical “blue laws” are regarded by some as barriers to economic growth in the communities that most need the economic boost.  Others argue that they are unconstitutional and are in direct violation of the Full Faith and Credit Clause of the US Constitution.

Everywhere, it seems that one group or another is critical of particular laws and wants them reformed or abandoned.  Someone who has not studied the law will usually apply a victim analysis when justifying criminal laws. Laws, they would assert, are designed to protect people from harm.  Those harms can be physical, psychological, and economic, but there is always a victim to which we can point. Civil libertarians are quick to point out that many of the controversial crimes they wish to see abolished are victimless crimes. What do Martha Stewart and Ted Bundy have in common? They broke the law. What else? Not much at all. It seems that there is little commonality that defines the essence of what it means for an act to be criminal.

Previewing The General Elements of Crimes

For law students, practitioners, and criminal justice professionals, understanding the elements of crimes is not a mere academic endeavor—it’s a necessity. Each crime has distinct elements that must be proven beyond a reasonable doubt for a conviction. This rigorous standard ensures the fair application of law and underscores the need for a thorough understanding of criminal elements. This section will delve into the foundational elements that constitute crimes, why they matter, and how they vary depending on the intent behind the legislation.

Foundational Elements of Every Crime

Generally, crimes are made up of certain key elements, often comprising at least three: the criminal act (actus reus), the criminal intent (mens rea), and the concurrence of the two. These elements serve as the building blocks of offenses, shaping the work of everyone in the criminal justice system, from police officers to prosecutors.

Actus Reus: The Criminal Act

The term “actus reus” refers to the physical act of the crime. Whether it is theft, assault, or any other offense, there must be an actionable deed committed by the perpetrator. The act serves as a tangible proof of the criminal conduct.

Mens Rea: The Criminal Intent

Mens rea signifies the mental state or the intent behind committing the act. This could range from negligence and recklessness to knowing and purposeful actions. Prosecutors must prove that the defendant had the requisite state of mind to commit the crime, making mens rea a critical element in every criminal case.

Concurrence: Act Meets Intent

Simply having a criminal intent or committing an illegal act is not sufficient for a crime to occur. There must be a concurrence, meaning the criminal act must be performed with criminal intent. The two must coincide for an individual to be charged and convicted.

When Additional Elements Come into Play

For crimes that are based on preventing a harmful result, two more elements come into the picture: causation and harm. In such instances, not only must the act and intent be present, but they must also result in a specific harm that the legislation aims to prevent.


Causation links the defendant’s actions directly to the resultant harm. It must be proven that the bad outcome occurred because of what the defendant did, adding another layer of complexity to the case.


In legal terminology, “harm” refers to the adverse outcome or the damage caused by the criminal act. This could be physical injury, financial loss, or other types of damage that the law aims to prevent.

The Role of Attendant Circumstances

Attendant circumstances are special conditions that must be fulfilled for an act to be considered a crime. For example, in common law, burglary must occur at night; otherwise, it’s considered trespassing. These circumstances add specificity and context to crimes, allowing for a more nuanced application of the law.

Mastering the Elements

Understanding the elements of crimes is essential for anyone in the legal profession. It provides the basis for dissecting criminal statutes into their component parts, leading to a more comprehensive understanding of the law. By mastering these elements, you arm yourself with the tools needed to interpret and apply criminal laws effectively and justly. This in-depth comprehension can significantly impact your career, whether you are a budding law student, an experienced attorney, or a criminal justice professional.

References and Further Reading

Actus Reus.Encyclopedia of Crime and Justice.


Powell v. Texas, 392 U.S. 514 (1968).

Robinson v. California, 370 U.S. 660 (1962).

Modification History

File Created:  07/12/2018

Last Modified:  09/05/2023

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This work is licensed under an Open Educational Resource-Quality Master Source (OER-QMS) License.

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