Criminal law is the foundation of the criminal justice system. It defines prohibited behaviour within a community and provides punishment for individuals who commit crimes.

A crime is any act or omission that goes against laws that forbid it. There are many proscribed behaviours in criminal law, including details of what constitutes them, how the government proceeds against an individual facing specific criminal charges, the rights of accused persons and possible punishments if found guilty.

Understanding criminal law and how the legal system works is important for criminal lawyers and other legal professionals who regularly deal with crime-related matters. However, other people should at least know the basics of criminal law because understanding what is prohibited and how the justice process works might be useful when least expected.

To help you understand criminal law, we’ll explore its purpose, principles, categories, elements of crimes and more.

Ready? Let’s dive in.

Table of Content

Purpose of Criminal Law

Principles of Criminal Law

Substantive Criminal Law Vs Procedural Law

The Definition of Criminal Conduct

The Elements of Crime


Purpose of Criminal Law

The ultimate purpose of the Canadian Criminal Law is to maintain a peaceful, just and safe society. It achieves this by establishing a system of prohibitions, sanctions, penalties and procedures that help the government to fairly and appropriately deal with any conduct that causes or threatens to cause harm to individuals or society.

Criminal law portrays a community’s values. When one is found guilty of undesirable behaviour, the sentence imposed is a means to communicate and instil these communal values as articulated by the Criminal Code.

Let’s now look at the characteristics that make up criminal acts.

Principles of Criminal Law

Criminal law is based on certain fundamental principles that enable it to achieve its purpose. These principles make the general part of criminal law that applies to all crimes, forming the building blocks used to construct criminal acts.

Let’s take a look at some of these principles:

  • Criminal Act (actus reus): for a crime to occur, one must act or fail to act as required by law. One cannot be punished for having bad thoughts but rather for acting on them.
  • Criminal Intent (mens rea): To be found guilty of a crime, one must have the required criminal mental state (a guilty mind). The individual knowingly, negligently, recklessly or purposely causes harm to another person or society.
  • Concurrence: The criminal act and a guilty mind must accompany each other. As stated earlier, one cannot be punished for having bad thoughts if they do not act on them.
  • Causation: The accused’s act must cause the harm required to label it a criminal act. For example, serious injuries in case of aggravated assault. One must show cause (defendant) and effect (on individual or society)
  • Responsibility: Criminal law should clearly state prohibited acts, and this information should be easily and reasonably accessible to individuals. This allows one to choose whether to follow or violate the law. Also, it should provide the level of responsibility required to be found guilty of the offence. One cannot be punished for an act that is not criminalized, i.e., no crime without law, no punishment without law.
  • Uniformity: Criminal law should be applied equally to anyone accused of criminal acts. For example, persons facing the same criminal charge- where the relevant conditions are similar- should receive the same punishment.
  • The Burden of Proof: Unless otherwise stated, the government (prosecution) bears the responsibility of proving all the elements of a crime beyond a reasonable doubt.
  • Defences: Criminal guilt is not simply imposed on a person after criminal accusations are brought against them. The accused have a chance to defend themselves. One is not convicted if the act is justified (e.g., self-defence in an assault case) or excusable (e.g., mental illness, hence no criminal culpability).

Now that you know the principles of criminal law, let’s explore its categories.

Substantive Criminal Law Vs Procedural Law

Criminal law comprises Substantive Law and Procedural Law. The two complement each other. How? Well, let’s a look at each of them, and you’ll understand how.

Substantive Law

Substantive Criminal Law comprises the following elements:

  • the precise definition of criminal acts
  • specific punishments for the criminal acts
  • classification of different crimes into summary offences, indictable offences and hybrid offences
  • principles and doctrines used to judge a crime, e.g., necessity, willful blindness and self-defence.

In Canada, the Criminal Code, the Controlled Drug and Substance Act and the Canada Revenue Agency Act are some of the sources of Substantive Laws. They define prohibited conduct and provide punishment for those who break the law. The Criminal Code is the most important source of Substantive Criminal Law in Canada.

Procedural Law

Procedural Law is the second half of criminal law. It set out the following elements:

  • The rules and procedures followed by the government when charging, prosecuting and punishing a person accused of a crime.
  • The means to make and administer Substantive Law

The main purpose of Procedural Criminal Law is to provide a fair and consistent way of enforcing substantive laws. Procedural law is a means of delivering justice in criminal law while protecting the individuals facing criminal charges.

The Definition of Criminal Conduct

Principle of Legality

The principle of legality is important in criminal law as it helps determine criminal conduct and protects individuals against the state’s power. It’s implemented in four ways:

  • No crime without the rule of law. Only the law can define a crime and specify a punishment. In other words, you cannot face charges for an act that is not prohibited.
  • No retroactive application of the law. To be charged and convicted of a crime, the law prohibiting that crime must already be in effect. No law, no crime.
  • Criminal statutes should be strictly interpreted and applied without any analogical extension. This means that in case of any ambiguities in a statute, it should be interpreted narrowly, favouring the accused. However, the interpretation should not defeat the purpose of the statute.
  • Criminal law should be simple, clear, understandable, accessible, and unambiguous. All statutes should define crimes in a simple but specific language, giving everyone a fair warning about prohibited behaviour.

Protection Against Double Jeopardy

In Canada, a defendant cannot be prosecuted twice for the same offence. This restriction is referred to as protection against double jeopardy. Whether you’re acquitted o convicted of an offence, you cannot face further criminal charges for it.

Statutes of limitation

Can you face criminal charges years after engaging in prohibited conduct? Well, it depends on the category of the crime.

The statute of limitations sets a time within which the police can charge you with a crime. After this time has passed, one cannot face criminal charges.

There’s no umbrella statute of limitations in Canada, i.e., no restriction on when the police can charge you for all criminal offences.

However, there is a 12-month statute of limitation for summary offences as provided for by the Criminal Code. In other words, one cannot be charged with a pure summary conviction offence 12 months after the alleged crime occurred.

On the other hand, there is no statute of limitation for indictable offences. Therefore, one can face criminal charges years or decades after breaking the law.

Requirements of Jurisdiction

Criminal jurisdiction refers to a court’s capacity or power to take well-founded legal actions. In Canada, there are two jurisdictions, the federal and provincial. In criminal law, there are three requisites when it comes to a court’s exercise of criminal jurisdiction:

  • Subject matter: does the law give jurisdiction to a certain court to try a case?
  • Person: acquiring jurisdiction over the accused person by arresting them or when they surrender to a court’s jurisdiction
  • Territory: if one breaks the law in a certain province, e.g., Ontario, they are usually charged in that territory. In other words, the territory where the crime occurs confers the court territorial jurisdiction over that criminal case.

The Elements of Crime

For an act to be a crime, it must fulfil these elements: the mental element (Mens rea) and the prohibited act (Actus rea).

The Mental Element

A guilty mind, or Mens rea, is a major part of any criminal offence. In criminal law, there’s no culpability unless the requisite state of mind for that specific offence is established. The prosecution can establish a guilty mind by showing intention, negligence, knowledge, willful blindness or maliciousness.

Prohibited Act

For an act or omission to be a crime, it must be prohibited by criminal law and fall within the definition of that specific crime. As noted earlier: no crime without law, no punishment without law.

It’s good to note that ignorance of the law does not exclude one from criminal culpability. Therefore, claiming you were not aware that your actions or omissions were forbidden by law is not an acceptable excuse or defence for your conduct.

Strict Liability

Some offences do not require the prosecution to prove “a guilty mind” on the defendant’s part. Only the criminal conduct element is required to prove the crime. Such crimes include some regulatory and public welfare offences.