Criminal law, in its widest sense, includes substantive criminal law, the operation of penal institutions, criminal procedure and evidence, and police investigations (see Criminal Investigation). More precisely, the term refers to substantive criminal law - a body of law that prohibits certain kinds of conduct and imposes sanctions for unlawful behaviour.

In general, the prohibitions contained in criminal offences are concerned with protecting the public at large and maintaining the accepted values of society. These values include the preservation of morality (through such laws as the obscenity and prostitution offences); protection of the person (eg, murder and assault offences); protection of property (eg, theft and fraud offences); preservation of the public peace (eg, incitement to riot and causing a disturbance offences); and preservation of the state (eg, treason offences).

Underlying the various theories explaining the purpose of criminal law is the basic premise that criminal law is a means by which society reaffirms its values and denounces violators. A change in values entails a change in the types of conduct society wishes to prohibit. Amendments to the Criminal Code in areas such as sexual offences, abortion, pornography and punishment for murder demonstrate that Canadian criminal laws develop, at least to some extent, in response to changing social values.

Criminal law has also changed in response to technical advances, eg, recent amendments to the Criminal Code concerning theft of telecommunications, and credit card fraud and provisions regulating the use of wiretap surveillance.

The sources of substantive criminal law in Canada are limited. Most offences are created by the Criminal Code, which prohibits conviction of an offence at common law (except for the offence of contempt of court). Criminal offences are also contained in other related federal statutes, such as the Narcotic Control Act, the Food and Drugs Act, and the Young Offenders Act.

A number of federal offences and offences under provincial statutes (eg, liquor and highway control offences) and municipal bylaws (eg, parking tickets, pet control) are not criminal offences in the true sense, but are generally processed through the courts in the same general manner as criminal offences. These offences are often called "regulatory offences."

Origin of Criminal Law

According to the Constitution Act, 1867, Parliament was granted legislative jurisdiction with respect to "the criminal law, except for the Constitution of the Courts of Criminal Jurisdiction but including the Procedure in Criminal Matters." This particular constitutional provision gives the federal government power to pass laws concerning criminal law and procedure.

The provinces can pass legislation dealing with subjects in which provinces have constitutional power and can enforce these laws (under s92 of the Constitution Act, 1867) by imposing "punishment by fine, penalty, or imprisonment." It is therefore possible to have "provincial offences" enacted by the province, but if these offences conflict with a statute passed under the federal government's criminal-law power, the federal law is generally paramount.

The provinces were also granted legislative competence concerning "the administration of justice in the Province, including the Constitution, Maintenance and Organization of Provincial Courts, both of Civil and of Criminal Jurisdiction."

Therefore, policing, appointment of prosecutors, administration of the courts and appointment of lower-court judges are provincial responsibilities. The appointment of county and supreme court judges is a federal responsibility under s96 of the Constitution Act (see Judiciary).

Criminal law and procedures are subject to provisions of the Canadian Charter of Rights and Freedoms. The Charter is part of the Constitution of Canada. The Constitution Act, 1982, holds that "the Constitution of Canada is the Supreme Law of Canada, and any law that is inconsistent with the provisions of the Constitution is, to the extent of the inconsistency, of no force or effect."

The courts must therefore measure all legislation, including the Criminal Code and related statutes, against the Charter's provisions. The Charter may directly affect criminal-law procedure and may have an impact on the definition of certain crimes and the resulting punishment.

It is a cardinal principle of Canadian criminal law that there can be no crime or punishment except in accordance with fixed, predetermined law. To this end, the courts have concluded that a criminal prohibition must be in existence at the time of the alleged crime and that the offence created by such prohibition must be clearly ascertainable. If the provision providing for the criminal offence is ambiguous, then it will be interpreted by the courts in favour of the accused.

The application of the criminal law by police, prosecutors, judges and juries depends very much upon the facts of each case. Courts seek to apply the law consistently. Judges, when determining the law applicable to a case, are influenced greatly by previous court decisions, ie, "precedents" involving similar situations. The fact that judges tend to follow precedents creates consistency in the interpretation of the statutory law and helps to indicate how the law will be interpreted in the future.

An appeal system exists in the criminal courts not only to correct injustices but also to avoid inconsistencies in the application of the law itself. Previous legal precedents, upon which the judge hearing the case feels bound, can be overruled by higher courts if it can be demonstrated that the precedent is either wrongly decided or out of date.

There are many legal wrongs that are not crimes. They fall in the field of civil law and are the basis of private law suits. A civil action is a private legal proceeding brought to court by one person against another. A civil court can compensate the aggrieved party by providing monetary damages or, in some cases, can cause the defendant to rectify the wrong caused.

In criminal law a crime is a wrong against the community as a whole rather than against the individual victim; consequently a criminal prosecution is launched by the state and the victim is merely a voluntary (and sometimes reluctant) witness for the prosecution. However, in recent years Parliament has passed legislation substantially amending the sentencing provisions of the Criminal Code, by which more attention will be paid to victims of crime and which will provide for such measures as restitution and compensation to victims (see Criminal Code).

Constituents of a Crime

A crime may be divided into 2 elements: the prohibited conduct or act (actus rea) and the required mental element (Mens Rea). Generally, before an act can become a crime it must fall precisely within the definition of the offence. It may be an act of omission as well as commission. However, in recent years Parliament has passed legislation substantially amending the sentencing provisions of the Criminal Code, by which more attention will be paid to the victims of crime and which will provide for such measures as restitution and compensation to victims (see Criminal Code).

Mens rea ("guilty mind") is a difficult concept. It is not defined in the Criminal Code and in Canada, depending upon the particular offence, the prosecution may be required to prove a state of mind that may include either intention (the most common state of mind required to be proven in criminal cases), advertent negligence, knowledge, recklessness, wilful blindness or more specific states of mind contemplated by such words as "maliciously" or "fraudulently."

Nevertheless, there is still an overriding principle in the criminal law that there is no criminal responsibility unless the guilty mind required by the offence can be proven. The idea of "guilty mind required by an offence" has been refined in light of the Charter. For example, the Supreme Court of Canada has held that murder is so serious a crime that it would be fundamentally unjust to convict someone of murder who did not, at the time of the killing, have a murderous state of mind. The Court then struck down, as unconstitutional, those sections of the Criminal Code which permitted murder convictions where the intent to kill had not been proven. Thus, the Charter has given rise to the principle that the mens rea to be proven must "fit" the crime. Most criminal trials are in fact contested on the basis of whether the accused had the requisite state of mind rather than whether he actually performed the prohibited act. This state of mind has to be proven with the same certainty as the other ingredients of a crime, and the prosecution must therefore present a clear picture of what was in the individual's mind at the time the offence was committed.

In order to ease this difficulty, some criminal law statutes create or recognize a presumption or inference regarding the required mental element; however, many of these "reverse onus clauses" have recently been declared unconstitutional as various courts have ruled the provisions conflict with the rights of an accused as set out in the Charter. But the Charter has impacted on the mental element required for so-called "strict liability" offences. The Supreme Court has held that where an offence carries with it the potential for imprisonment, if the accused has diligently, though unsuccessfully, attempted to avoid the prohibited action then he or she cannot be convicted of it. Such a conviction would offend fundamental justice.

In regulatory offences, the law distinguishes 3 different forms of the mental element. If the legislation uses words such as "wilfully" or "intentionally," the legislature is presumed to have intended that the mental element required is an intent to commit the prohibited act. For the second class of regulatory offences, eg, those relating to public health, highway traffic, environmental law, and safety in the workplace, it is only necessary that the accused knows that his acts or omissions may result in the offence being committed. But the Charter has impacted on the mental element required for so-called "strict liability" offences. The Supreme Court has held that where an offence carries with it the potential for imprisonment, if the accused has diligently, though unsuccessfully, attempted to avoid the prohibited action then he or she cannot be convicted of it. Such a conviction would offend fundamental justice.

The final category of regulatory offences (strict liability offences) requires no mental element whatsoever and there is consequently no necessity of proving any fault on the part of the accused; the Crown need only prove that the accused was responsible for the prohibited act.

Under Canadian law, criminal responsibility may be placed on parties other than the actual perpetrator. Persons who aid, assist or counsel the commission of an offence can be found guilty of the same offence as the perpetrator. Also, attempting or conspiring to commit a crime or counselling an offence that is not actually committed are all criminal offences. However, courts have held that mere preparation to commit a crime is not sufficient to constitute an attempt.

In any criminal trial, one of the most important principles of all is the presumption of innocence. According to this principle, the Crown must prove the guilt of the accused, and it is not for the accused to establish innocence. Furthermore, the Crown must establish guilt beyond a reasonable doubt. This principle has been enshrined in the Charter and is considered by many to be one of the most important protections for the individual against the state.

Defences

Both the Criminal Code and the common law recognize a number of defences to criminal charges.

Defence of Capacity
In certain cases, individuals will be found not guilty, even though the prohibited act and the intention to commit this act are proven, because the individuals are deemed incapable by law of committing the offence in question. For example, any child under the age of 12 years cannot commit a criminal offence. As well, any boy or girl under the age of 18 must be tried in the juvenile courts under the Young Offenders Act unless he or she is ordered to stand trial in the adult court by a juvenile court judge (see Juvenile Justice Systems).

Insane persons are also considered to be incapable of committing criminal offences. Section 16 of the Criminal Code presumes that everyone is sane but permits defendants to establish that they were insane at the time of the commission of an offence.

If insanity is established, then the person is found to be not guilty by reason of insanity and is detained indeterminately for treatment until a government-appointed board of review determines that the individual may return to society. In addition, an individual cannot be found guilty of a crime if he or she is unfit to stand trial because of mental illness. These individuals are held in mental hospitals until they recover sufficiently to understand the legal proceedings against them.

Defences that Negate Proof of the Prohibited Act
To prove that someone has committed a prohibited act, it must be demonstrated that the act or omission was consciously and voluntarily committed. Defences that fall into this category include accident, duress (ie, a person has been compelled to commit an offence because his or his family's life or safety have been threatened), and automatism, which may be generally defined as involuntary, unconscious behaviour where the physical movements are performed without volition or without exercise of the will (eg, a person, as a result of an external blow to the head, commits a prohibited act while in an unconscious or semiconscious state, or a person who commits an offence while sleepwalking).

Defences that Negate Proof of Mens Rea
In most "true" criminal offences, the Crown must prove that, before committing the act, the accused actually intended to achieve the unlawful result. The law recognizes that certain factors raise a reasonable doubt that the person intended to achieve the unlawful consequence. The defences usually mentioned in this context include intoxication (which is commonly used to reduce a murder charge to the lesser offence of manslaughter), honest mistake of fact, and, in some very limited circumstances, mistake of law. However, in the vast majority of factual situations, ignorance of the law provides no defence.

Defences of Excuse or Justification
With these defences, the law recognizes human frailty and weaknesses and will hold that the accused was either justified in committing the unlawful act or is at least partially excused for the conduct. Examples of defences of justification are self-defence and defence of property. In 1990 the Supreme Court of Canada found the defence of self-defence can apply to a battered woman who kills her batterer at a time when her life is not in imminent danger. Recognition of the "battered woman syndrome" expanded the scope of evidence which could be used to prove self-defence to include the psychological effects of battering on women charged with assaulting or even killing their battering partners. Defences of excuse include obedience to authority (eg, a soldier who believes he is simply obeying lawful orders), provocation (which only applies in murder cases and involves a killing committed in the heat of passion, which has been caused suddenly by a wrongful act or insult sufficient to deprive an ordinary person of his self-control), and entrapment (in which the person has committed the offence under pressure by police authorities).

Sanctions

If an individual is convicted of a criminal offence, the presiding judge must impose a sentence. In Canada, judges have a great deal of discretion in sentencing. There are few mandatory minimum sentences and the maximum sentences given in the Criminal Code are generally set quite high. A judge may choose an absolute discharge, conditional discharge, probation, suspended sentence, fines or imprisonment.

In determining an appropriate sentence, judges must consider a multitude of factors and remind themselves that each sentencing is unique because the individual characteristics of each crime and offender are never the same. Some of the more important factors that they take into consideration when imposing sentence are the degree of premeditation, whether the accused has a previous criminal record, the gravity of the crime committed, the degree of participation of the offender in the crime, the incidence of this particular crime in the jurisdiction, past sentences imposed for the same or similar offences, and the age, lifestyle and personality of the offender.

Large-scale changes to the sentencing provisions of the Criminal Code have been made recently and more are expected shortly. These changes are a response to a growing awareness in Canadian society that the process of sentencing offenders must account for the needs and interests of victims of crime and that effective alternatives to imprisonment are a likelier route to rehabilitation of an offender.