Fundamentals of Criminal Law by Adam J. McKee

This content is released as a draft version for comment by the scholarly community.  Please do not distribute.

Many states recognize the defense of infancy. Infancy asserts that the defendant is not subject to criminal prosecution because he or she is too young to commit a crime. The policy supporting the infancy defense is the belief that juvenile defendants are too immature to form criminal intent (this is the same logic that underpins the idea that a victim cannot consent to a statutory rape). Despite the ancient common law origins of the doctrine, the modern infancy defense is mostly statutory and can be perfect or imperfect, depending on the state.  Be sure to note that the legal concept of an infant is far broader in scope than the everyday use of the word. Anyone under the legal age of majority can potentially be an “infant” under this doctrine.

The trend today is to consider anyone under the age of 18 as a juvenile. States divide up the jurisdiction of criminal defendants between juvenile courts and adult courts. Juvenile court systems generally retain jurisdiction over criminal defendants under the age of sixteen, seventeen, or eighteen, depending on the state.  Most states now have exceptions to this general rule, allowing for the waiver of juveniles to adult court when crimes are regarded as especially heinous. The Model Penal Code specifies that “a person shall not be tried for or convicted of an offense if: (a) at the time of the conduct charged to constitute the offense he was less than sixteen years of age.  When the offender is under the age of 16, the MPC specifies that the juvenile court shall have exclusive jurisdiction. Because of rules regarding which court will have jurisdiction, the defense of infancy is rarely raised as a defense per se. It is built into the procedural law of each jurisdiction.

Infancy Under Ancient Common Law

Under the ancient common law rules, criminal defendants were divided into three age groups for the purpose of assessing criminal culpability as a function of age.  

Those under the age of seven were deemed incapable of forming criminal intent, and could not be criminally prosecuted.

Defendants between the ages of seven and fourteen were provided a rebuttable presumption that they lacked the mental capacity to form criminal intent.

Once a defendant turned fourteen, he or she was subject to an adult criminal prosecution.

Modern statutes codify the adult criminal prosecution standard for different age groups. Some states follow the ancient common law doctrine, setting up rebuttable and irrebuttable presumption schemes based on the offender’s age.  

  Several factors are commonly used to determine whether or not a case should be waived to adult court.  Among these are the nature of the offense, the sophistication that committing the offense requires, the defendant’s criminal history, and the threat the defendant poses to public safety.

Term of Art:  Waiver

When a juvenile court has jurisdiction in a case, that jurisdiction must be relinquished if the juvenile is to be prosecuted as an adult. This process is called a waiver. Juvenile courts can have exclusive jurisdiction over minors under eighteen, or concurrent or simultaneous jurisdiction with adult courts, depending on the state.  States vary as to the particulars of the waiver procedure. Some states allow judges to use discretion in granting the waiver, while others grant this power to the prosecutor.

Key Terms



References and Further Reading

“Excuse: Theory.” Encyclopedia of Crime and Justice.


“Insanity Defense.” West’s Encyclopedia of American Law.


“The Insanity Defense Among the States.”  Findlaw.  


“M’Naghten Rule.” West’s Encyclopedia of American Law.


“Durham Rule.” West’s Encyclopedia of American Law.


“Excuse: Duress.” Encyclopedia of Crime and Justice.  


“Excuse: Intoxication.” Encyclopedia of Crime and Justice.


“Mistake of Fact.” West’s Encyclopedia of American Law.


“Mistake of Law.” West’s Encyclopedia of American Law.


“Entrapment.” Encyclopedia of Crime and Justice.



Ake v. Oklahoma, 470 U.S. 68 (1985)

Montana v. Egelhoff, 518 U.S. 37 (1996)

Kent v. United States, 383 U.S. 541 (1966)  


Jacobson v. United States, 503 U.S. 540 (1992)  


Modification History

File Created:  07/17/2018

Last Modified:  05/03/2021

[ Back | Content | Next]

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

Open Education Resource--Quality Master Source License


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Doc's Things and Stuff uses Accessibility Checker to monitor our website's accessibility.