One Crime, Two Codes: How the BNS-BNSS-BSA Transition Shaped India's Constitutional Docket in 2025

The situation, in human terms

Imagine two men arrested in the same week for causing a death by rash driving. One incident happened in June 2024; the other, in August 2024. The first man's case will be tried, from FIR to judgment, under the Indian Penal Code, 1860 and the Code of Criminal Procedure, 1973. The second man's case proceeds entirely under the new Bharatiya Nyaya Sanhita, 2023 (BNS) and the Bharatiya Nagarik Suraksha Sanhita, 2023 (BNSS). Same offence, same court, same judge perhaps — but two different statute books, two different section numbers, and in places, two different procedures. This is the quiet, unglamorous constitutional reality that Indian criminal courts have lived through in 2025, and it is the backdrop against which many of the Supreme Court's year-end 'landmark judgments' round-ups have been compiled.

What happened

On 1 July 2024, India's three colonial-era criminal statutes — the IPC, the CrPC, and the Indian Evidence Act, 1872 — were substituted, for future conduct, by the BNS, the BNSS, and the Bharatiya Sakshya Adhiniyam (BSA) respectively. The new codes were not made retrospective wholesale: offences committed before the switchover continue, as a rule, to be investigated, tried, and punished under the old law, while offences after that date fall under the new one. Through 2025 — the first full calendar year of the new regime — the Supreme Court and High Courts have had to repeatedly work out how the two systems interact: which provisions of the new procedural code apply even to pending 'old law' cases, how old IPC section numbers map onto new BNS numbers in judgments and orders, and how new rights created only under BNSS (such as tighter timelines for undertrial detention) are to be treated for people whose alleged offence predates the code but whose trial is ongoing today. Several of the judgments compiled in this year's 'landmark judgments' lists touch this transition, even where the headline issue is something else — bail, sentencing, or evidentiary procedure.

The law behind it

The starting point is the commencement and application clause of each new code. BNS Section 1 and BNSS Section 1 fix the date from which the new substantive and procedural law respectively took effect. Crucially, both codes contain express savings provisions rather than a clean repeal. BNS Section 358 is the 'Repeal and savings' clause for the penal code, and BNSS Section 531 performs the same function for the procedural code — both preserve the operation of the old IPC and CrPC for anything done or any proceeding pending before the appointed date, so that acts already completed under the old regime are not thrown into legal limbo. This is reinforced by BNSS Section 4, which governs the trial of offences under the BNS 'and other laws', clarifying that offences will be tried according to the procedural code in force, subject to these savings.

This statutory scheme sits directly on top of a constitutional guarantee: Article 20(1) of the Constitution provides that no person can be convicted of an offence except for violation of a law in force at the time the act was committed, nor be subjected to a penalty greater than what was prescribed under that law then. This is India's constitutional bar on ex post facto criminal liability. It means Parliament could not, even if it wished, apply BNS's substantive offence definitions or enhanced punishments retrospectively to conduct that occurred before 1 July 2024 — the savings clauses in BNS Section 358 and BNSS Section 531 are, in that sense, giving statutory effect to what Article 20(1) already commands. Read alongside Article 21's guarantee of personal liberty — which the Supreme Court has long held includes the right to a fair and speedy criminal process — the transition raises a distinct question: what happens to purely procedural improvements introduced by BNSS, which do not create new criminal liability but only better protect the accused?

Several such procedural upgrades are worth knowing. BNSS Section 479 introduces a clearer cap on the period an undertrial prisoner may be detained before being entitled to release, extending special solicitude to first-time offenders. BNSS Section 187 governs what happens when police investigation cannot be completed within twenty-four hours, feeding into the default (statutory) bail framework. BNSS Section 35 tightens the conditions under which police may arrest without a warrant, and BNSS Section 37 requires a designated police officer at every station to maintain arrest-related information for public access. BNSS Section 48 obliges the police to inform a relative or friend of an arrested person about the arrest. BNSS Section 105 mandates audio-video recording of search and seizure, a safeguard against evidence tampering and false implication. BNSS Section 530 permits trials and proceedings to be conducted in electronic mode, formalising the digitisation of courtrooms. Because these are procedural and beneficial rather than punitive, courts have generally leaned towards treating them as applicable even to prosecutions for older offences that continue after 1 July 2024, since procedural law is conventionally understood to operate on pending proceedings unless it prejudices the accused — a principle distinct from, but complementary to, the strict substantive-law rule under Article 20(1).

On the substantive side, the exercise of renumbering matters more than it might seem. What was murder under Section 302 IPC is now punished under BNS Section 103, with the definition of the offence itself carried in BNS Section 101 (paralleling old Section 300 IPC). Judgments, chargesheets, and even lawyers' submissions must now correctly track which numbering applies to which case, and errors here have real consequences — a wrongly cited provision can affect everything from cognizability to sentencing range under BNSS Section 21, which allocates offences to the courts empowered to try them.

How we got here

The IPC, CrPC, and Evidence Act were products of the 1860s and 1870s, drafted for a colonial administration and retained with amendments through Independence. Parliament replaced all three within the same legislative exercise, packaging codification of new offences (organised crime, terrorism, mob lynching-type provisions, and revised offences against women) together with procedural modernisation (electronic trials, tighter timelines, forensic mandates for serious offences). The new codes were notified to commence on 1 July 2024, but Parliament deliberately chose not to make them retrospective for substantive offences, both as a matter of policy and because Article 20(1) would have made a fully retrospective penal code unconstitutional in any event. The result was the two-track system now bedding down — old cases proceeding to their conclusion under IPC/CrPC, new cases opening under BNS/BNSS, and courts having to hold both frameworks in their heads simultaneously.

What it means in practice

For an ordinary citizen, the practical effect is that the year on which an alleged offence occurred determines which law applies to them — an FIR registered in 2025 for a fresh incident will cite BNS and BNSS sections, while an accused facing a years-old pending trial will still hear IPC and CrPC section numbers in court, even in late 2025. This bifurcation demands precision from police stations, prosecutors, and defence lawyers alike; a chargesheet citing the wrong code is not a mere formality but can be challenged as legally defective. For UPSC and judiciary aspirants, 2025 has effectively doubled the syllabus: candidates must know both the old and new section numbers, understand the savings clauses that govern which law applies to a given fact pattern, and be alert to how constitutional provisions like Article 20(1) and Article 21 constrain and shape this transition. Any answer on 'recent developments in criminal law' that ignores the transitional mechanics under BNS Section 358 and BNSS Section 531 would be incomplete.

What to watch

Expect continued judicial clarification through 2026 on precisely which BNSS procedural safeguards apply to pending 'old law' trials, and on how courts should treat mixed situations — for instance, an offence under the old IPC investigated using new BNSS procedural tools. Some uncertainty remains around whether every state and union territory brought certain ancillary rules and forms into force on exactly the same date, which can generate localized disputes about which code governed a given arrest or search. Readers should treat any claim about a settled, uniform position on retrospective application of specific BNSS provisions with caution until the Supreme Court authoritatively resolves it; this piece deliberately does not predict how any pending question will be decided.