The Rajasthan government implemented a Sales Tax Incentive Scheme in 1987 to promote industrial growth by offering tax exemptions to new industries. Initially, oil extraction and manufacturing industries were eligible ... for these benefits, as they were not listed in the exclusionary annexure. However, in May 1990, the government amended the scheme, excluding oil industries from the tax exemptions under both the Rajasthan and Central Sales Tax Acts. This move followed concerns that the scheme was negatively affecting existing industries by incentivizing new ones, leading to the closure of older units. Despite this, in 1991, the government partially restored benefits under the Central Sales Tax Act. The respondents, who had started operations after the 1990 exclusion, sought to claim the benefits and challenged the validity of the notification in court. The case involved a series of legal proceedings, including decisions by the High Court and Supreme Court, addressing the validity of the notification and the applicability of doctrines like promissory estoppel.