Criminal Law

You find yourself in the back seat of a police car. You have been arrested for a crime. Thanks to criminal law, you are now a part of the American justice system. Hopefully, you don't actually find yourself in a situation like that, but read on further to learn some of the basics of criminal law, which may or may not help you should you find yourself in a similar predicament!

Criminal Law Criminal Law

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Table of contents

    Figure 1 Criminal Law Crime Scene Ribbon and Police Lights StudySmarterFigure 1. Crime Scene Ribbon and Police Lights, Pixabay

    Criminal Law Definition

    Criminal law refers to the branch of law consisting of any acts or behaviors seen as offensive to the public, government, or state in violation of criminal statutes.

    Criminal Law vs. Civil Law

    To better understand the definition of criminal law, it might be helpful to learn the fundamental differences between criminal and civil laws.

    Civil Law

    Civil law is the branch of law consisting of non-criminal acts and legal actions between private individuals or corporations.

    Criminal LawCivil Law
    Illegal activity is calledCrimeTort
    Initiated byState or Federal GovernmentPrivate Parties; Corporations
    Burden of proofBeyond a reasonable doubtPreponderance of evidence
    Penalties Incarceration; probation; finesFines; never incarceration.


    Tort refers to an injury to a person or property, including assault and battery, and may include emotional harm as well as physical harm.

    Figure 2 Criminal Law Woman Handcuffed StudySmarterPerson Handcuffed, No copyright restrictions (Pixabay)

    Types of Criminal Law

    There are generally two crime classifications in criminal law common at the state and federal levels.

    1. Felonies

      • This is the most severe type of crime

      • Felonies are split into violent and non-violent categories

      • Punishment amounts to more than one year in prison

      • Examples:

        • Violent Crimes

          • Manslaughter, murder, aggravated assault

        • Drug Crimes

          • Sale/manufacturing/distribution of drugs

        • Property Crimes

          • Arson, auto theft, larceny

        • Kidnapping

    2. Misdemeanors

      • Punished by less than one year in prison

      • Minor offense

      • Examples:

        • Petty theft

        • Drug possession

        • Prostitution

        • Vandalism

        • Trespassing

    Capital Felonies are types of felonies that are subject to the death penalty.

    Figure 3 Criminal Law Thief escaping through window StudySmarter Thief escaping through a window, Pixaby

    Criminal Offenses

    Most crimes can be placed into specific categories. There are six main criminal offense categories.

    1. Crimes Against Persons

      • Examples: Assault, kidnapping, murder

    2. Crimes Against Property

      • Examples: Shoplifting, theft, arson

    3. Crimes Against Morality (Victimless Crimes)

      • Examples: Prostitution, illegal gambling, indecent exposure

    4. Statutory Crimes

      • Examples: DUI (Driving Under the Influence [of alcohol], reckless driving, hit and run, public intoxication

    5. Financial/White Collar Crimes

      • Examples: Forgery, insider trading, identity theft

    6. Inchoate Crimes

      • Examples: Conspiracy and attempt to commit a crime.

    Types of Crimes

    There are two moral classifications of crimes. These are Mala Prohibita and Mala in Se.

    Mala in Se

    Mala prohibita crimes are defined as inherently immoral. These are crimes that should not be done because they are morally wrong. Some examples of mala prohibita are murder, rape, kidnapping

    Mala Prohibita

    Mala in Se are those crimes that are only considered crimes because they are prohibited by statutes. Some examples of Mala In Se are traffic tickets, tax evasion, and theft.

    Introduction to Criminal Law

    At this point, you may wonder, who defines laws? In the United States, legislatures are the ones that define crimes and punishments. The federal government has codified federal crimes in Title 18 of the US Code. Some federal criminal offenses include arson, counterfeiting, embezzlement, espionage, kidnapping, and genocide.


    Codification is the process of forming a legal code.

    US Code

    US Code is consolidation and codification by subject matter of the general and permanent laws of the United States.1

    Each state also has its own criminal code. Therefore, criminal offenses and punishments differ from state to state and even from state to federal. Many states use the Model Penal Code's guidelines and regulations to set up their own state codes.

    Model Penal Code (MPC)

    The American Law Institute created the MPC in 1962 to be used as a reference with the hope that multiple states would adopt similar provisions and have some commonality. Currently, 37 states have adopted some provisions from the MPC.

    Figure 4 Criminal Law Lady Justice on Desk StudySmarterFigure 4. Lady Justice on Desk, Pixaby

    Elements of Criminal Law

    For someone to be charged with a crime without reasonable doubt, two elements must be demonstrated: Actus Reus and Mens Rea.

    Actus Reus & Mens Rea

    Actus Reus is Latin for a guilty act. Actus Reus questions whether or not someone committed a crime. This can usually be proven through physical evidence, witness testimony, and forensics.

    There are three elements to Actus Reus:

    1. Voluntary act - doing an act willingly

    2. Possession - having illegal items

    3. Omission - not acting when required to do so, under law.

    Mens Rea, on the other hand, is Latin for guilty mind. This one is more difficult of the two to prove because it involves figuring out what was inside the mind of the person in question, and lawyers must establish the person had motive and intent to commit a crime.

    There are four elements to Mens Rea (in other words, levels of culpability)

    1. Intent

      • Consciously wanting to commit an illegal act.

      • E.g. Kidnapping

    2. Knowledge

      • Consciously wanting to commit an illegal act with a specific result in mind.

      • E.g. Assault or premeditated murder

    3. Recklessness

      1. Committing an action knowing the risks involved

      2. E.g. DUI

    4. Negligence

      1. A person does not meet standard behavior.

      2. E.g. Child getting injured under the babysitter's watch.

    Strict Liability Offenses

    These types of offenses are criminal offenses regardless of whether the person had a motive or not. Therefore, mens rea doesn't have to be evidenced in court. Some examples of strict liability offenses are statutory rape, traffic offenses, and the sale of alcohol to minors.

    To charge a person with a crime, both Actus Reus and Mens Rea have to have occurred together. In other words, there has to be concurrence.

    Suppose John was on his way to murder Jennifer but ran her over on the way to murder her. This would not be considered murder because John did not intend to murder Jennifer with his car, which was an accident.

    Figure 5 Criminal Law Law Books and Gavel StudySmarterFigure 5. Law Books and Gavel, Pixaby

    Defendant Rights

    Defendants have rights that are guaranteed to them through the US Constitution. They are stated within the Fifth Amendment and Sixth Amendment.

    1. The Right to Remain Silent - to avoid being a witness to yourself.

    2. The Right to Confront witnesses - ability to cross-examine witnesses

    3. The Right to a Public Trial - allows family members and friends to be present in the courtroom.

    4. The Right to a Jury Trial - promotes fairness

    5. The Right to Speedy Trial - ensures timely sentencing

    6. The Right of Representation - gives the defendant the ability to have a defense

    7. Right of No Double Jeopardy - not being tried for the same crime twice.


    People accused of crimes have the right to defend themselves from these allegations. Here are a few examples of some defenses people make under criminal law:

    Defenses based on Mental State

    Defenses based on Justification

    Defenses based on Mistakes

    InsanitySelf DefenceMistake of law - Ignorance of laws
    IntoxicationDefense of PropertyMistake of Fact - Ignorance of facts
    DuressDefense of Others

    Criminal Law Concept

    Criminal law is the framework of the United States criminal justice system. Criminal law encompasses any actions that lead to arrest, trial, and/or incarceration.

    Importance of Criminal Law

    Criminal law serves a vital role in maintaining order in society. It protects individuals and society from harmful acts of others by prohibiting specific actions. It punishes people who commit harmful acts, and those punishments help deter others from committing the same infraction. It does all this while attempting to impose fair justice. Without these simple things, chaos would reign in society.

    Criminal Law - Key takeaways

    • Criminal Law is the branch of law consisting of any acts or behaviors seen as offensive to the public, government, or state in violation of criminal statutes.
    • There are two main types of crimes: Felonies and Misdemeanors
    • Actus Reas and Mens Rea have to be demonstrated to be convicted of a crime
    • Mens rea doesn't apply to Strict Liability Offenses
    • Some common defenses used by suspects are insanity, intoxication, and self-defense.
    • Mala prohibita crimes are defined as inherently immoral; Mala in Se are those crimes that are only crimes because they are prohibited by statutes
    • Legislatures are the ones who define crimes.


    1. Office of the Law Revision Council. United States Code.
    Frequently Asked Questions about Criminal Law

    What is the difference between civil and criminal law?

    Criminal law refers to crimes, while civil law refers to torts 

    What is criminal law?

    Criminal Law is the branch of law consisting of any acts or behaviors seen as offensive to the public, government, or state in violation of criminal statutes.

    What is the meaning of the criminal law?

    Criminal law is the framework of the United States criminal justice system. Criminal law encompasses any actions that lead to arrest, trial and incarceration. 

    What is an example of criminal law?

    An example of criminal law is being tried for Murder. 

    What are the characteristics of criminal law?

    There are two types of categories crimes fall under Mala prohibita and Mala in Se. 

    Test your knowledge with multiple choice flashcards

    What kind of Burden of Proof does Criminal Law have to show? 

    What are the two main classifcation of crimes? 

    Which of the following are examples of crimes against morality? 


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