When an amendment is made by the parliament in the constitution, it can be challenged if it violates the principle of basic structure of constitution. But, the question is that if a statue is passed by the parliament or state legislature, whether its validity can also be challenged on the basic of principle of basic structure of the constitution?
We can understand the answer by referring some judgments.
D.C. Wadhwa & Ors. v. State of Bihar & Ors. 
In Dr. D.C. Wadhwa & Ors. v. State of Bihar & Ors. [1987 (1) SCC 378], the Bihar Intermediate Education Council Ordinance, 1985 was struck down as unconstitutional and void on the basis that it was repugnant to the constitutional scheme.
In that case Government of Bihar was found to have “made it a settled practice to go on re-promulgating ordinances from time to time and this was done methodologically and with a sense of deliberateness”.
Immediately at the conclusion of each session of the State legislature, a circular letter would be sent by the Special Secretary in the Department of Parliamentary Affairs to all the Departments intimating to them that the session of the legislature had been got prorogued and that under Article 213 clause (2)(a) of the Constitution all the ordinances would cease to be in force after six weeks of the date of reassembly of the legislature and “that they should therefore get in touch with the Law Department and immediate action should be initiated” to get all the concerned ordinances re-promulgated before the date of their expiry.
Supreme Court in above fact situation held and observed as under: –
“When the constitutional provision stipulates that an ordinance promulgated by the Governor to meet an emergent situation shall cease to be in operation at the expiration of six weeks from the reassembly of the legislature and the government if it wishes the provisions of the ordinance to be continued in force beyond the period of six weeks has to go before the legislature which is the constitutional authority entrusted with the law-making function, it would most certainly be a colourable exercise of power for the government to ignore the legislature and to repromulgate the ordinance and thus to continue to regulate the life and liberty of the citizens through ordinance made by the executive.
Such a stratagem would be repugnant to the constitutional scheme, as it would enable the executive to transgress its constitutional limitation in the matter of law-making in an emergent situation and to covertly and indirectly arrogate to itself the law-making function of the legislature.”
Noticeably the above view was taken about the Ordinances issued by the State of Bihar in the face of clear violation of the express constitutional provisions
L. Chandra Kumar v. Union of India & Ors. 
In this case not only was the Constitutional amendment depriving High Court of its jurisdiction under Article 226 and 227 (from decisions of Administrative Tribunal) struck down on the ground that taking away judicial review from the High Courts violated the basic structure doctrine but even Section 28 of the Administrative Tribunal Act 1985, providing for “exclusion of jurisdiction of Courts except the Supreme Court under Article 136 of Constitution” was also struck down.
Indra Sawhney v. Union of India & Ors. (2000)
In this case, a bench of 3 Judges of supreme Court expressly held in that case that a State enacted law (Kerala Act on creamy layer) violated the doctrine of basic structure. The question before the Court essentially was as to whether the right to equality guaranteed by the Constitution and the law declared by the Supreme Court could be set at naught by a legislative enactment. The issues raised also concerned the legislative competence of the State Legislature.
In paragraph 65 of the judgment, it was observed as under: –
“Parliament and the legislature in this country cannot transgress the basic feature of the Constitution, namely, the principle of equality enshrined in Article 14 of which Article 16(1) is a facet.
Whether the creamy layer is not excluded or whether forward castes get included in the list of backward classes, the position will be the same, namely, that there will be a breach not only of Article 14 but of the basic structure of the Constitution. The non-exclusion of the creamy layer or the inclusion of forward castes in the list of backward classes will, therefore, be totally illegal. Such an illegality offending the root of the Constitution of India cannot be allowed to be perpetuated even by constitutional amendment. The Kerala Legislature is, therefore, least competent to perpetuate such an illegal discrimination. What even Parliament cannot do, the Kerala Legislature cannot achieve.”
Smt. Indira Nehru Gandhi v. Raj Narain, 
It is well settled that legislation can be declared invalid or unconstitutional only on two grounds namely, (i) lack of legislative competence and (ii) violation of any fundamental rights or any provision of the Constitution.
A.N. Ray, CJ, in Indira Nehru Gandhi’s case (supra), observed in paragraph 132 as under: –
“The contentions on behalf of the respondent that ordinary legislative measures are subject like Constitution Amendments to the restrictions of not damaging or destroying basic structure, or basic features are utterly unsound. It has to be appreciated at the threshold that the contention that legislative measures are subject to restrictions of the theory of basic structures or basic features is to equate legislative measures with Constitution Amendment. “
In paragraph 153 of his judgment, he ruled as under: –
“The contentions of the respondent that the Amendment Acts of 1974 and 1975 are subject to basic features or basic structure or basic framework fails on two grounds.
First, legislative measures are not subject to the theory of basic features or basic structure or basic framework. Second, the majority view in Kesavananda Bharati’s case is that the Twenty-ninth Amendment which put the two statutes in the Ninth Schedule and Article 31-B is not open to challenge on the ground of either damage to or destruction of basic features, basic structure or basic framework or on the ground of violation of fundamental rights.”
In same case, K.K. Mathew, J. in Paragraph 345 of his separate judgment ruled as under: –
“There is no support from the majority in Kesavananda Bharati’s case for the proposition advanced by Counsel that an ordinary law, if it damages or destroys basic structure should be held bad or for the proposition that a constitutional amendment putting an Act in the Ninth Schedule would make the provisions of the Act vulnerable for the reason that they damage or destroy a basic structure constituted not by the fundamental rights taken away or abridged but some other basic structure. And, in principle, I see no reason for accepting the correctness of the proposition.”
State of Karnataka v. Union of India & Anr. [(1977)
A Constitution Bench (7 Judges) in State of Karnataka v. Union of India & Anr. [(1977) 4 SCC 608] held, per majority, (paragraph 120) as under: –
” in every case where reliance is placed upon it, in the course of an attack upon legislation, whether ordinary or constituent (in the sense that it is an amendment of the Constitution), what is put forward as part of “a basic structure” must be justified by references to the express provisions of the Constitution”
In Paragraph 197, it was observed as under: – “if a law is within the legislative competence of the Legislature, it cannot be invalidated on the supposed ground that it has added something to, or has supplemented, a constitutional provision so long as the addition or supplementation is not inconsistent with any provision of the Constitution.”
Kuldip Nayar v. Union of India, (2003)
In this case, while considering the submission of counsel that 2003 amendment to ‘People representation act, 1951) that omission of requirement of domicile for the candidate of Rajya Sabha member, violates the doctrine of basic structure, the court held that,
“The doctrine of ‘Basic Feature’ in the context of our Constitution, does not apply to ordinary legislation which has only a dual criterion to meet, namely:
(i) It should relate to a matter within its competence;
(ii) It should not be void under Article 13 as being an unreasonable restriction on a fundamental right or as being repugnant to an express constitutional prohibition.
The basic structure theory imposes limitation on the power of the Parliament to amend the Constitution. An amendment to the Constitution under Article 368 could be challenged on the ground of violation of the basic structure of the Constitution. An ordinary legislation cannot be so challenged. The challenge to a law made, within its legislative competence, by Parliament on the ground of violation of the basic structure of the Constitution is thus not available to the petitioners.”