This paper provides a comprehensive analysis of the doctrine of the separation of powers, tracing its evolution from classical political philosophy to contemporary constitutional practice. By establishing a comparative baseline through the jurisprudence of the United Kingdom such as the defense of parliamentary sovereignty in Miller II and the United States highlighting the formalist protection of judicial power in Plaut and Loper Bright the study examines how mature democracies navigate inter-branch conflicts. The primary focus is directed toward the Republic of India, where a Westminster parliamentary model of executive-legislative integration intersects with robust judicial review. Despite the Constituent Assembly's design of a "seamless web" of governance, the research demonstrates that the Indian constitutional framework faces deep structural vulnerabilities. The analysis details how this balance is continuously threatened by executive overreach including "pocket vetoes" on judicial appointments, "Ordinance Raj," and "sealed cover" jurisprudence alongside aggressive legislative overrides and the systematic tribunalisation of justice, which subordinates adjudicatory bodies to executive ministries. While the Indian higher judiciary has actively countered these encroachments through the Basic Structure doctrine and expansive judicial activism, the paper argues that relying solely on judicial intervention is insufficient and carries the risk of democratic overreach. Ultimately, the study synthesizes comparative institutional mechanisms and proposes targeted structural reforms such as regulating post-retirement judicial appointments, restricting retrospective legislative overrides, and unifying tribunals under independent judicial control to fortify judicial autonomy and restore lasting constitutional equilibrium.