What Is Criminal Law?

Criminal law is a set of rules that regulates the apprehension, charging, and trial of suspected criminals. It also establishes penalties for crimes committed.


Some find criminal law’s general justification in its concern with harm or wrongs. But this does not explain why the law is needed.


The laws of a jurisdiction define what constitutes criminal behavior, as well as how it may be punished. These laws differ widely between and even within jurisdictions, depending on the values of a society and its willingness to sanction certain types of behaviour. For example, a felony in one jurisdiction might be prosecuted as a misdemeanor in another.

In general, a criminal act must be an act of mens rea (intent) and result in harm or injury to a victim, with a causal link between the two. Intention and harm are the core elements of most crimes, although some criminal codes also criminalize association with or involvement in a crime that does not come to fruition — concepts such as conspiracy and aiding and abetting.

Criminal law must balance the rights of individual citizens with the public’s interest in preventing crime and ensuring that those guilty of an offense are punished appropriately. Generally, punishment should accomplish the objectives of retribution, deterrence, incapacitation and rehabilitation. However, different jurisdictions place varying values on these objectives, and may disagree about what sort of penalty is sufficient for an offence. Moreover, changing times and social attitudes may make some activities that were once considered criminal illegal in the future. This is sometimes the case with abortion and homosexual conduct between consenting adults, which are now lawful in most Western countries.


The criminal law consists of laws that prohibit certain types of conduct. It focuses on punishing criminals and protecting society from harm. It also aims to deter crime and reform offenders. It is primarily enforced by police, security, and prosecutors, and it relies on public funds to operate. It is different from civil law, which involves legal disputes and compensation for injuries and property loss.

Most crimes are statutory, meaning they are forbidden by statute. This includes drugs, alcohol, and traffic offenses. Other criminal laws include the law against treason, and laws against conspiring to commit a crime or aiding in the commission of one. These laws are mainly prosecuted by the federal government, but state governments may have their own versions of them.

There are many reasons to doubt that criminal law is primarily justified by preventing moral wrongdoing. For one, it would entail massive invasions of privacy and involve the law taking sides in conflicts that should be resolved by other means. Furthermore, it is easy to find examples of wrongdoing that are not related to morality, such as wrongful sporting injuries or botched conspiracies.

Other writers look for criminal law’s distinctiveness elsewhere. They claim that its uniqueness does not lie in its provision for punishment but rather in the fact that it expresses censure in a way that other bodies of law cannot (Husak 2008, 92-95). For example, the verdict that DD committed a criminal act conveys to others that DD is a reprehensible person.


Criminal law regulates the apprehension, charging, and trial of suspected criminals and sets penalties and modes of treatment for convicted offenders. Its purpose is to deter future crime by frightening the defendant and the public at large. Its goal is also to correct and reform the offender. The penalties include imprisonment, fines, restitution and community service. Many criminal codes define crimes that affect the person, property and inchoate crimes, such as conspiracy, robbery, and murder. Crimes against property include conversion, embezzlement and theft. Many countries have laws that punish trespassing, fraud and other offences of dishonesty.

Some argue that criminal law has value because it helps to create a community with a shared self-understanding, and that the stability of any such community depends on compliance with its defining rules. The value of stable institutions, they argue, justifies criminal liability for breaking them (Chiao 2016).

Others criticize the Kantian justification for criminal law on the grounds that it is unduly expansive: much moral wrongdoing, including some that generates secondary duties to suffer or protect, is not the business of the criminal law. For example, failing to help one’s lazy friend move house might be a moral wrong, but it is no business of the criminal law (Duff 2014b; Husak 2014). Other arguments claim that punishment discharges duties owed to the community. For example, it ensures that those in positions of power cannot wrong others with impunity and reduces the risk of vindictiveness leading to violent conflict in which all lose out (Moore 1997, 170-172; Tadros 2011c).


Criminal law includes not just the substantive laws that define the crimes, but also the procedures associated with criminal cases. This means that there are specific rules that must be followed during the investigation, arrest, filing of charges, trial and appeal. This process is governed by the constitution, state and federal laws and by court decisions. These rules help to ensure that the system is fair and that individuals’ rights are protected during the process.

Before an arrest can take place, prosecutors must determine whether probable cause exists that the accused committed the crime. This involves a thorough investigation of all the facts surrounding the case. It will include interviewing victims, witnesses and possibly the person of interest. Investigators will also evaluate, document and photograph the crime scene. They may also conduct tests on trace, physical and scientific evidence including DNA.

Once the prosecution has determined that they have sufficient evidence, the accused will be charged with a crime at an initial hearing called an arraignment. This is usually done in person. During this time, the defendant is informed of the charges against him/her and the judge sets bail (if applicable) for those eligible to do so. The accused is also entitled to “discovery” from the prosecution which consists of the sharing of information, documents and evidence related to the case.