Step 1: Understanding the Concept:
This question deals with the interpretation of Article 16 of the Constitution, which guarantees equality of opportunity in matters of public employment. The jurisprudence has evolved to understand that formal equality is not enough, and the principle can accommodate reasonable classification and affirmative action to achieve substantive equality.
Step 2: Detailed Explanation:
In the case of State of Kerala v. N.M. Thomas (1976), the Supreme Court significantly broadened the understanding of equality under Article 16. The case involved a rule that gave temporary exemption to employees belonging to Scheduled Castes and Scheduled Tribes from passing a departmental test for promotion.
The majority judgment held that Article 16(1), which guarantees equality of opportunity, is a facet of the broader principle of equality in Article 14. The Court observed that the concept of equality of opportunity is not a sterile one. It is a concept that admits of classification and differentiation. The Court stated that "equality of opportunity is not an absolute right" and that it "admits of discrimination with reasons".
The court reasoned that to treat unequals as equals is to perpetuate inequality. Therefore, providing preferential treatment to the historically disadvantaged SC/ST communities to bring them on par with others was not a violation of Article 16(1) but a fulfillment of its true spirit. This case was a precursor to the expansive view of reservation and affirmative action later articulated more fully in \textit{Indra Sawhney}. While the other cases also deal with equality, the specific observation that "equality of opportunity admits discrimination with reasons" is famously associated with the reasoning in \textit{N.M. Thomas}.