Key Constitutional Doctrine: Basic Structure Doctrine: Parliament has amending power under Article 368, but cannot alter or destroy the essential features or basic structure of the Constitution (democracy, rule of law, federalism, secularism, judicial review).

Key Constitutional Doctrine: Substantive Due Process: The procedure depriving a person of life or personal liberty under Article 21 must be just, fair, and reasonable, not arbitrary. Articles 14, 19, and 21 form an indivisible Golden Triangle of human freedoms.

Key Constitutional Doctrine: Fundamental Right to Privacy: Privacy is a fundamental right emanating from Article 21 (Life and Liberty) and Part III of the Constitution, protecting informational, bodily, and spatial privacy against State intrusion.

Key Constitutional Doctrine: Custodial Violence Safeguards: Laid down 11 mandatory procedural safeguards during arrest and detention (Arrest memo with date/time, right to inform family within 8-12 hours, mandatory medical checkup every 48 hours, visible name tags for police officers). Codified in BNSS Sections 36-39.

Key Constitutional Doctrine: Mandatory Registration of FIR: Under Section 154 CrPC (now Section 173 BNSS), police have a mandatory statutory duty to register an FIR if information discloses the commission of a cognizable offence. Preliminary inquiry allowed only in limited cases within 14 days.

Key Constitutional Doctrine: Safeguards against Routine Arrest: Prohibited routine and mechanized arrests for offences punishable with up to 7 years imprisonment (including Sec 498A / 85 BNS). Police must serve Section 35(3) BNSS Notice of Appearance and record reasons in writing before arresting.

Key Constitutional Doctrine: Speedy Release of Seized Property & Vehicles: Police cannot keep seized vehicles, articles, or currency rotting in police station yards. Magistrate must order photographs, valuation bond, and release the property to the rightful owner on Supurdari within 6 months.

Key Constitutional Doctrine: Police Reforms & Public Complaints Authorities: Directed creation of State Security Commissions, transparent merit selection of DGP, fixed 2-year tenure for police chiefs/SHOs, separation of investigation from law & order, and Police Complaints Authorities (PCA) at State and District levels.

Key Constitutional Doctrine: Right to Speedy Trial & Free Legal Aid: Declared that speedy trial and 100% free legal representation to impoverished undertrial prisoners are integral components of the right to life and personal liberty under Article 21 and Article 39A.

Key Constitutional Doctrine: Immediate Disqualification of Convicted Legislators: Struck down Section 8(4) of the Representation of the People Act as unconstitutional. Any sitting MP or MLA convicted and sentenced to 2 or more years imprisonment stands disqualified immediately from the date of conviction.