sum and substance

Pith and substance

Pith and substance is a legal doctrine in Canadian constitutional interpretation used to determine under which head of power a given piece of legislation falls. The doctrine is primarily used when a law is challenged on the basis that one level of government (be it provincial or federal) has encroached upon the exclusive jurisdiction of another level of government.

The analysis has two parts. First, the law at issue is characterized by its most dominant feature, and second, the law is assigned to one of the enumerated matters listed in section 91 or 92 of the Constitution Act, 1867.

Dominant feature

The first step in a pith and substance has been described in numerous ways. It determines the substance, essential character, dominant feature, or true meaning of the law. This involves examining both the intended purpose of the law as well as the legal effect of the law on rights and obligation upon the public. . The purpose can be found through the wording of the law, the mischief that the law was intending to address as well as the overall social context for the law's introduction. Examination of the actual effect is useful in determining if the law was "colourable," that is, whether the law, in substance, addresses a matter completely different from what the law addresses in form. For example, in R. v. Morgentaler (1993) the province of Nova Scotia passed a law prohibiting abortion clinics under the guise that it was protecting health services, while the Supreme Court of Canada found that in substance they were attempting to ban abortions.


Once the law has been characterized it must be assigned to one of the two heads of power. The matters in the exclusive domain of the federal government are enumerated under section 91 of the Constitution Act, 1867 and matters in the exclusive domain of the provincial government are enumerated under section 92. Whether the characterization of a law fits within one of the enumerated matters depends on the breadth given by the court to each matter.

Ancillary effects doctrine

In many circumstances where a law is found to be valid under the pith and substance test the law may also have some incidental or ancillary effects upon matters outside of the government's jurisdiction. In such cases the intruding provisions of the law will only be upheld if they satisfy the "rational connection" test.

The full test was articulated in General Motors v. City National Leasing (1989). The standard used depends on the seriousness of the encroachment. The Court must consider the degree the valid legislative scheme intrudes upon the other government's jurisdiction. If it is a minor intrustion, then the provision need only be "rationally connected." Otherwise for serious encroachments the provisions must be "truly necessary" or "essential" to the functioning of the law.

Use outside of Canada

The Pith and Substance doctrine as applied in the jurisprudence of the Judicial Committee of the Privy Council, effectively the British Imperial Court of Appeal, has been carried to other Commonwealth federations. It is used in India under the present Constitution. It was also used in Northern Ireland under the Government Ireland Act 1920. The substance of the doctrine has been cast in legislative form in the Scotland Act 1998 for the purpose of devolution to Scotland.


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