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 Constitution Act, 1867, which established a federal constitution for Canada, enumerated in Sections 91 and 92 the topics on which the Dominion and the Provinces could respectively legislate. Notwithstanding that the lists were framed so as to  be fairly full and comprehensive, soon, it was found that the topics enumerated in the two sections overlapped, and the Privy Council repeatedly had to pass on the constitutionality of laws made by the federal and provincial legislatures. It was in this situation that the Privy Council evolved the doctrine that, for deciding whether an impugned legislation was "intra vires", regard must be had to its pith and substance. Thus, if a statute is found in substance to relate to a topic within the competence of the legislature, it should be held to be "intra vires" even though it might  incidentally trench on topics not within its legislative competence. The extent of the encroachment on matters beyond its competence may be an element in determining whether the legislation is colourable: whether in the guise of making a law on a matter within its competence, the legislature is, in truth, making a law on a subject beyond its competence. However, where that is not the position, the fact of encroachment does not affect the vires of the law even as regards the area of encroachment. Nature of pith and substance analysis. The analysis must answer two questions: Essential character. The first  task in the pith and substance analysis is to determine the pith and substance or essential character of the law: The pith and substance analysis is not technical or formalistic it is essentially a matter of interpretation. The court looks at the words used in the impugned legislation as well as the background and circumstances surrounding its enactment. In conducting this analysis, the court should not be concerned with the efficacy of the law or whether it achieves the legislature’s goals. Assignment. There are two significant principles to be used in determining whether a matter falls within a particular  federal or provincial jurisdiction: 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. A law found to be valid under the pith and substance analysis of the law may also have some  incidental effects upon matters outside of the government's jurisdiction. This is tolerated, as a law is classified by its dominant characteristic. The modern approach to Canadian Constitutional interpretation is to allow a fair amount of interplay and overlap into the other level of government's jurisdiction. Ancillary effects doctrine. In many circumstances, however, a law that is found to be invalid under the pith and substance analysis may still be saved by using the doctrine of necessarily incidental or ancillary effects. In such cases, the intruding provisions of the law will only be upheld if they satisfy the "rational  connection" test. The doctrine was first articulated in "Cushing v. Dupuy", where the Judicial Committee of the Privy Council held that certain rules of civil court procedure could be prescribed under the federal bankruptcy power. It was subsequently confirmed in "Tennant v. The Union Bank of Canada", where rules governing warehouse receipts with respect to bank loans could be prescribed under the federal banking power. The full test was articulated in "General Motors v. City National Leasing" by Dickson CJ, where he summarized and outlined the analysis to be used in that regard in future cases: In certain cases, it  may be possible to dispense with some of the aforementioned steps if a clear answer to one of them will deal with the issue. For example, if the provision in question has no relation to the regulatory scheme, the question of its validity may be quickly answered on that ground alone. 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 the Indian Constitution. It was also used in Northern  Ireland under the Government of Ireland Act 1920. The substance of the doctrine has been cast in statutory form in the Scotland Act 1998 for the purpose of devolution to Scotland. It was also used in Australia until 1964, when the High Court case of "Fairfax v Commissioner of Taxation" overruled its use by an alternate method. In India. It is used in the Indian Constitution. The doctrine has been applied in India also to provide a degree of flexibility in the otherwise rigid scheme of distribution of powers. The reason for adoption of this doctrine is that if every  legislation were to be declared invalid on the grounds that it encroached powers, the powers of the legislature would be drastically circumscribed. Cases relating to Pith and Substance.- Citation in the matter of M/s. Sky Gourmet Catering Private Limited V/s Tax Authorities (Commercial Tax and Service Tax) in the matter of Writ Appeal No. 671 to 726 of 2011 (T-Res) decided on 18th day of April, 2011 by Hon'ble High Court of Karnataka at Bangalore may also be seen.