In the U.S. legal system, a person may be punished for a crime only if she has been convicted of a crime, that is, found criminally liable. This article discusses what constitutes criminal liability. For a discussion of civil liability, see our article on Civil Liability.
A crime is an offense against the state, as defined by each state's criminal laws. No act is a crime until it is recognized as such by society and written into the states' and federal criminal codes. We may think certain acts have always been crimes or are treated as crimes everywhere, but that is not the case. For example, U.S. law historically did not recognize the rape of a wife by her husband until relatively recently (and some states continue to limit a husband’s liability for nonconsensual sex with his wife. See The History of Marital Rape Laws.)
So, a crime is a matter of definition by the society in which a person commits an act; an act is a crime only if a state or the federal government defines it as one. In most states, crimes are described as either felonies (more serious crimes) or misdemeanors (less serious crimes, such as vandalism).
Liability is the responsibility for a crime and for the penalty society exacts for the crime. Another word for liability is accountability. This explains the cliché that a person who has committed a crime must “pay her debt to society.” A crime is viewed as a harm to the society that has cost it something (not necessarily in dollar terms) and the criminal incurred the debt for that cost. Society accounts for the debt by imposing a penalty upon the criminal, such as prison time.
A person may be found liable for a crime if the prosecution proves that she a) committed the criminal act (such as taking property that was not hers), and b) had the required intent to hold her accountable (such as, for theft, intent to deprive the owner of the property).
In order to hold someone to account for a crime, the prosecutor must prove that she harbored the required level of criminal intent (called mens rea). In the example above, the prosecutor must prove that the defendant intended to wrongfully deprive the rightful owner of the property when she took of possession of it.
In a civil case, by contrast, no criminal intent is required. Indeed, many civil actions involve allegations that the defendant acted merely negligently, harming the plaintiff. The reason for the distinction is that civil cases involve disputes between individuals, not acts against the state, and the possible penalty to the defendant is usually strictly monetary.
Usually, criminal liability rests upon the person who directly committed the act. But, liability for a crime may reach beyond those directly involved in a criminal act. For example, “felony murder” laws make those involved in a felony that results in a death (such as the getaway driver who helps accomplices flee a botched armed robbery) liable for the death even if they did not “pull the trigger” or otherwise directly cause the victim’s demise.
In order to convict a person of a crime, the state must usually prove liability in addition to the fact that an act occurred. In other words, in order to prove theft, the state must prove that the defendant took property belonging to another and that the defendant took the property with the intent to deprive the owner of it. But, by simply engaging in certain conduct, a person may be found criminally liable for some crimes regardless of intent. An example is the crime of statutory rape. A person may be convicted of statutory rape even if the victim consented to the sexual contact (and, in some states, even if the defendant did not know the victim was under age). Thus, the prosecution need not prove that the defendant intended to rape the victim in order to convict the defendant; the very fact of the sexual conduct (the act alone) is sufficient to support a conviction.
Criminal liability law also recognizes situations in which the person who personally, directly engaged in the criminal act should not be held liable for the crime. Essentially, even though certain people committed a criminal act, they should not be held to account for it. The most obvious example is that of a person who is not guilty of a crime by reason of mental incapacity. Another group exempted from certain criminal liability is minors. The rationale for exempting such individuals from liability is that these people are unable to form the type of intent required to make it fair to hold them to account for the crime.
A person found criminally liable, by being convicted of, or pleading guilty to, a crime may be sentenced to serve time in jail or prison, to pay a fine, or both. In most states, the prison term for a felony is one year or more and for misdemeanors less than one year. In addition (or, possibly, in the alternative), the sentencing judge may order the person convicted to undergo drug or alcohol treatment, anger management or other counseling, and/or to abide by terms of probation (such as drug testing). A person convicted of certain sex crimes may also be required to register as a sex offender and abide by other terms upon release, such as periodic reporting to local authorities and staying away from schools, playgrounds, and other facilities where children are present.
The law on criminal liability varies depending on the particular crime charged, the jurisdiction in which the person is charged, and other factors specific to the situation (such as the defendant’s age). For questions about what is required to hold someone liable for a certain crime, check the article on that crime and in the state in question on this site.