Criminal law concerns the system of legal rules that define what conduct is classified as a crime and how the government may prosecute individuals that commit crimes. Federal, state, and local governments all have penal codes that explain the specific crimes that they prohibit and the punishments that criminals may face. Individuals who violate federal, state, and local laws may face fines, probation, or incarceration. Lawsuits against criminals are initiated by prosecuting attorneys who act on behalf of the government to enforce the law.
A crime is any act or omission of an act in violation of a law forbidding or commanding it. Most crimes are defined by statute, and they vary tremendously across different states and counties. The Model Penal Code (MPC) provides a good overview of the most common types of crimes, while the U.S. Code provides a list of all federal crimes. For a list of crimes in your state or local municipality, it is best to check your local penal code.
While specific criminal acts may vary by jurisdiction, they can be broadly characterized as “felonies” and “misdemeanors.” Felonies include more serious crimes, like murder or rape, and are usually punishable by imprisonment of a year or more. Misdemeanors are less serious offenses and are punishable by less than a year of imprisonment or fines.
Prosecution of Crimes
Unless a crime is a strict liability crime (meaning that no particular mental state is required), statutes typically break crimes down into two elements: an act (the “actus reus”) and a mental state (“mens rea”), such as knowingly or recklessly. In order to be convicted of a crime, a prosecutor must show that the defendant has met both of these elements. For example, larceny is the taking of the property of another with the intent to deprive them of it permanently. Thus, the defendant must have committed the act of taking the property and have done so with the mental intention to take the property of another (as opposed to believing that the property belonged to him).
It is not enough for a prosecutor to suggest that the defendant committed a crime. Rather, the prosecutor is required to prove each and every element of a crime “beyond a reasonable doubt” in order for a defendant to be convicted. Police officers, prosecutors, and other government officials must also follow certain procedures in pursuing criminal activity. This is because all citizens have certain constitutional rights that the government must respect and protect. If these rights are not respected, it may prevent a prosecutor from obtaining a conviction in a case. The United States Constitution sets forth these rights and the protections that are afforded to defendants. For instance, if a citizen is arrested for a suspected burglary, police officers may wish to question the individual in connection with the crime. However, the Fifth and Sixth Amendments of the Constitution protect citizens from unlawful questioning and interrogation by police officers, and cases such as Miranda v. Arizona, 384 U.S. 436 (1966), set forth the particular warnings, called Miranda rights, that police officers must provide before questioning can occur. Similarly, the Eighth Amendment of the Constitution protects criminal defendants from receiving punishment that is unusually cruel or excessive. Violation of any of these constitutional rightscan lead to the exclusion of evidence from a criminal trial, which in some cases may extinguish or weaken the prosecution’s case against the defendant.