On 4 May 1979, a three-judge Bench led by Justice P.N. Bhagwati laid down the multi-factor 'instrumentality or agency' test for when a body is 'State' under Article 12, and held that the State and its instrumentalities cannot depart arbitrarily from their own self-imposed standards when awarding contracts and largesse.
On 21 February 1975, a five-judge Constitution Bench held that statutory corporations created by Acts of Parliament — ONGC, LIC and IFCI in the consolidated appeals — are 'authorities' within Article 12, that regulations framed by such corporations under their enabling statutes have the force of law and bind both employer and employee as more than mere contract, and that public-sector dismissals made in breach of those statutory regulations are void, entitling the employee to reinstatement. Justice K.K. Mathew's concurring opinion laid the foundations of the 'instrumentality of State' doctrine that was elaborated in *R.D. Shetty* (1979) and *Ajay Hasia* (1981), and refined by the 7-judge Bench in *Pradeep Kumar Biswas* (2002). *Sukhdev Singh* remains the backbone of Indian public-employment jurisprudence.