Statutory rape is the "unlawful sexual intercourse with a person under the age of consent (as defined by statute), regardless of whether it is against that person's will." Generally, it is only the person over the age of consent who is convicted of a crime of statutory rape. Statutory rape is often a strict liability crime, meaning that mistake as to the age of the person is not a valid defense. The intention of many legislatures in adopting statutory rape as a strict liability crime was to protect minors of a specific age. Many legislatures believe that juveniles under a certain age are unable to appreciate the full magnitude and consequences of their actions, and thus cannot lawfully consent to sexual intercourse.
Model Penal Code
The Model Penal Code address the crime of statutory rape with section 213.3, corruption of minors and seduction. Under 213.3, a "male who has sexual intercourse with a female not his wife, or any person who engages in deviate sexual intercourse or causes another to engage in deviate sexual intercourse, is guilty of an offense if:
(a) the other person is less than  years old and the actor is at least [four] years older than the other person; or
(b)the other person is less than 21 years old and the actor is his guardian or otherwise responsible for general supervision of his welfare."
An offense under section 213.3(a) is a felony in the third degree whereas an offense under section (b) is a misdemeanor.
Variation by Jurisdiction
The California Penal Code section 261.5 addresses unlawful sexual intercourse with a person under 18. A minor under this statute is defined as someone under the age of 18. Any person who engages in an act of unlawful sexual intercourse with a minor who is not more than three years older or three years younger than the perpetrator, is guilty of a misdemeanor. Any person who engages in an act of unlawful sexual intercourse with a minor who is more than three years younger than the perpetrator is guilty of either a misdemeanor or a felony. This charge is punishable by imprisonment for up to one year. Any person 21 years of age or older who engages in an act of unlawful sexual intercourse with a minor who is under 16 years of age is guilty of either a misdemeanor or a felony. This crime is punishable by imprisonment in county jail for up to one year, or imprisonment in state prison for two, three, or four years.
In addition to the imprisonment terms, an adult who engages in unlawful sexual intercourse with a minor may also be fined a civil penalty, ranging from $2,000-$25,000USD. 
The Massachusetts Criminal Code cover statutory rape in section 23, rape and abuse of a child. The statute states that a person who unlawfully has sexual intercourse and abuses a child under 16 years of age, will be punished by imprisonment in the state prison for life or for any term of years that the court finds appropriate.
Because statutory rape is usually a strict liability crime, there are no defenses to the charge, other than a claim that the defendant did not perform the act itself (i.e. there is no actus reus).
Under the French Penal Code, rape is punishable by twenty years imprisonment when the victim is a minor under the age of 15.
In Vietnam, section 112 of the Penal Code addresses rape against children. A person who commits rape against a child between the ages of 13 to 16 will be sentenced to imprisonment for seven to fifteen years. However, if the rape is committed in one of the following circumstances, the imprisonment will increase to twelve to twenty years: if the perpetrator makes the victim pregnant, if the rape is incestuous in nature, or if the perpetrator is in a guardianship position as to the victim. An individual who rapes a child under the age of 13 will be sentenced to twelve to twenty years of imprisonment, life imprisonment or capital punishment. Offenders charged with rape against children may be banned from holding certain jobs or occupations.
- Black's Law Dictionary, 9th edition (2009)
- Stephanie A. Giggetts, Rape: Mistake as to the age of the female, American Jurisprudence, Second Edition (2010)
- Stephanie A. Giggetts, Rape: Statutory Rape, American Jurisprudence, Second Edition (2010)
- Model Penal Code, § 213.3, Corruption of Minors and Seduction (2001)
- California Penal Code, Title 9, Chapter 1, § 261.5(b)(2000)
- California Penal Code, Title 9, Chapter 1, § 261.5(c)(2000)
- California Penal Code, Title 9, Chapter 1, § 261.5(d)(2000)
- California Penal Code, Title 9, Chapter 1, § 261.5(e)(1)(2000)
- Massachusetts General Laws Annotated, Title 1, Chapter 265 (2008)
- French Penal Code, § 222-24 (1998), http://www.legifrance.gouv.fr/html/codes_traduits/code_penal_textan.htm