"The court must recognise the fundamental nature and importance of legislative process and accord due regard and deference to it, just as the legislature and the executive are expected to show due regard and deference to the judiciary. It cannot also be forgotten that our Constitution recognises and gives effect to the concept of equality between the three wings of the State and the concept of `checks and balances' inherent in such scheme."
28.One of the proven methods of examining the legislative competence of an enactment is by the application of doctrine of pith and substance. This doctrine is applied when the legislative competence of the legislature with regard to a particular enactment is challenged with reference to the entries in various lists. If there is a challenge to the legislative competence the courts will try to ascertain the pith and substance of such enactment on a scrutiny of the Act in question. In this process, it is necessary for the courts to go into and examine the true character of the enactment, its object, its scope and effect to find out whether the enactment in question is genuinely referable to the field of legislation allotted to the respective Legislature under the constitutional scheme. The said doctrine has come to be established in India and is recognized in various pronouncements of this Court as also of the High Courts. Where a challenge is made to the constitutional validity of a particular State Act with reference to a subject mentioned in any entry in List I, the court has to look to the substance of the State Act and on such analysis and examination, if it is found that in the pith and substance, it falls under an entry in the State List but there is only an incidental encroachment on topics in the Union List, the State Act would not become invalid merely because there is incidental encroachment on any of the topics in the Union List.
Again a five Judges' bench of this court while discussing the said doctrine in Kartar Singh v. State of Punjab (1994) 3 SCC 569 observed as under:
30.Though it is true that the State Legislature would not have power to legislate upon any of the matters enumerated in the Union List but as per the doctrine of Pith and Substance there could not be any dispute with regard to the fact that if it could be shown that the area and subject of the legislation is also covered within the purview of the entry of the State List and the Concurrent List, in that event incidental encroachment to an entry in the Union List will not make a law invalid and such an incidental encroachment will not make the legislation ultra vires the Constitution.
31. In Bharat Hydro Power Corpn. Ltd. v. State of Assam (2004) 2 SCC 553 the Doctrine of pith and substance came to be considered, when after referring to the catena of decisions of this Court on the doctrine it is laid down as under:
"18. It is likely to happen from time to time that enactment though purporting to deal with a subject in one list touches also on a subject in another list and prima facie looks as if one legislature is impinging on the legislative field of another legislature. This may result in a large number of statutes being declared unconstitutional because the legislature enacting law may appear to have legislated in a field reserved for the other legislature. To examine whether a legislation has impinged on the field of other legislatures, in fact or in substance, or is incidental, keeping in view the true nature of the enactment, the courts have evolved the doctrine of "pith and substance" for the purpose of determining whether it is legislation with respect to matters in one list or the other. Where the question for determination is whether a particular law relates to a particular subject mentioned in one list or the other, the courts look into the substance of the enactment. Thus, if the substance of the enactment falls within the Union List then the incidental encroachment by the enactment on the State List would not make it invalid. This principle came to be established by the Privy Council when it determined appeals from Canada or Australia involving the question of legislative competence of the federation or the States in those countries. This doctrine came to be established in India and derives its genesis from the approach adopted by the courts including the Privy Council in dealing with controversies arising in other federations. For applying the principle of "pith and substance" regard is to be had (i) to the enactment as a whole, (ii) to its main objects, and
(iii) to the scope and effect of its provisions. For this see Southern Pharmaceuticals & Chemicals v. State of Kerala (1981) 4 SCC 391, State of Rajasthan v. G. Chawla AIR 1959 SC 544, Thakur Amar Singhji v. State of Rajasthan AIR 1955 SC 504, Delhi Cloth and General Mills Co. Ltd. v. Union of India (1983) 4 SCC 166 and Vijay Kumar Sharma v. State of Karnataka (1990) 2 SCC 562. In the last-mentioned case it was held: (SCC p. 576, para 15) "15. (3) Where a law passed by the State Legislature while being substantially within the scope of the entries in the State List entrenches upon any of the entries in the Central List the constitutionality of the law may be upheld by invoking the doctrine of pith and substance if on an analysis of the provisions of the Act it appears that by and large the law falls within the four corners of the State List and entrenchment, if any, is purely incidental or inconsequential.""