A crime is an unlawful act punishable by the state.

How crimes are defined

• In the US today, crimes are defined within written laws.
• Local (city or county) laws are often called ordinances.
• State and federal laws are called statutes.
• Collections of statutes are often called codes. These may be organized according to content, as in California, where most crimes are defined within the Penal Code. However, many jurisdictions do not organize their statutes this way.
• There are also international laws, contained in treaties, but these have little impact on most people.
• Although similarities exist, the specifics of crimes vary greatly from one jurisdiction to another.
• Virtually all crimes consist of an actus reus—the specific act required for conviction under that law. For example, the actus reus for homicide is often the unlawful killing of a human being.
• Almost all crimes also require a specific mens rea—the mental state or degree of intent required for conviction under that law. For example, the mens rea for first degree murder is often willfully and with premeditation. In contrast, the mens rea for second degree murder (which has the same actus reus) is willfully and without premeditation. The mens rea for voluntary manslaughter (which also has the same actus reus) is recklessly.
• In addition to actus reus and mens rea, a crime may also contain additional elements. For example, a hate crime usually requires that the offender be motivated by the victim’s group.
• In order to obtain a conviction, the prosecutor must prove every element of a crime beyond a reasonable doubt.
• A person cannot face criminal charges for an act—no matter how harmful or appalling that act is—unless that act is specifically prohibited by law.

What distinguishes criminal law from civil law

• With criminal law, the case can be brought only by the government. With civil law, the aggrieved party brings the case (lawsuit).
• With criminal law, the standard of proof is beyond a reasonable doubt. With civil law, it’s generally preponderance of the evidence.
• With criminal law, the defendant may be punished—with fines, incarceration, or death, among other things. With civil law, the defendant pays damages to the plaintiff.
• The terminology is often different. For example, the person who brings the case is the state (or the United States) in criminal cases, the plaintiff in civil. The defendant is found guilty in a criminal case but liable in a civil one.
• Defendants in criminal cases get greater legal protections than defendants in civil cases. For example, civil defendants are not entitled to a government-paid attorney (although they can hire one of their own).
• Note that even minor infractions such as parking tickets and speeding citations are, technically, criminal rather than civil.

How crimes are graded

• The least serious crimes are called infractions. People generally cannot be incarcerated for infractions; fines are the usual punishment. Common examples of infractions include parking citations, speeding tickets, and violations of noise ordinances.
• The next most serious crimes are called misdemeanors. Usually, the maximum penalty for a misdemeanor is a year or less in jail (not prison).
• Felonies are the next most serious crimes. Their maximum penalties generally involve a year or more in prison (not jail). Felony convictions may also bring other serious consequences, such as disqualification from voting rights.
• The most serious crimes are capital felonies–those that have the death penalty as a possible sentence. In practice, the only capital felonies in the US today are murder and treason.
• Some crimes are called wobblers. Prosecutors can choose whether to charge these particular offenses as a misdemeanor or as a felony. These vary tremendously from state to state.

Kinds of crime

• Crimes against persons: Also called violent crimes. These include offenses in which a person is harmed or threatened with harm. This category includes murder, robbery, sexual assaults, and assault and battery. These crimes usually carry the most severe penalties.
• Crimes against property: These are offenses in which a person’s property is stolen or damaged. This includes burglary, larceny, and arson, among others.
• Public order crimes: Also called victimless crimes (although that name is somewhat controversial). These are offenses without a specific victim, but which are assumed to be harmful to society in general or to the person who commits them. Many of these are so-called morality offenses such as prostitution, gambling, and obscenity. Drug offenses are probably the most common public order crimes.
• Political crimes: These are crimes against the government. Immigration offenses are probably the most common in this category, which also includes treason, espionage, and terrorism, among others.