Preventive Arrest to Stop a Cognizable Offence Under the BNSS (Section 170): CrPC 151 Mapping (2026)
What Section 170 of the BNSS lets the police do to stop a cognizable offence before it happens, the old CrPC 151 it replaced, and the safeguards. Last verified October 2026.
Explainer · New Criminal Laws · BNSS
The police sometimes learn that a person is about to commit a serious offence, and that nothing short of stopping that person will prevent it. Acting too late means harm is done. Acting without limits means the power can be abused to detain people without a case. Indian criminal procedure balances this with a narrow power of preventive arrest. From 1 July 2024 it is Section 170 of the Bharatiya Nagarik Suraksha Sanhita (BNSS), which replaced Section 151 of the Code of Criminal Procedure (CrPC). This explainer explains the power, how it maps to the old law, and the safeguards that control it. Last verified October 2026.
- New code section: Section 170 of the BNSS, 2023, in force from 1 July 2024.
- Old law it replaced: Section 151 of the CrPC, 1973.
- What it does: lets a police officer arrest a person without a warrant to prevent a cognizable offence that cannot otherwise be prevented.
- Detention cap: 24 hours from arrest, unless further detention is authorised by law.
- Nature: a narrow preventive power, not an offence, so it carries no punishment of its own.
01The problem this power addresses
Prevention is sometimes the only real protection. If a cognizable offence is about to be committed and there is no other way to stop it, the police must be able to act at once. But an arrest without a case and without limits is a serious intrusion on liberty, so the power is kept narrow.
The tension is clear:
- The State must be able to stop a serious offence before it happens.
- A person must not be detained without a real and immediate reason.
Section 170 draws that line by setting strict conditions and a firm time limit on detention.
02What Section 170 BNSS is
Section 170 of the BNSS is the power of preventive arrest. A police officer who comes to know of a design to commit a cognizable offence may arrest the person, without orders from a Magistrate and without a warrant, if it appears that the commission of the offence cannot otherwise be prevented.
This is a procedure provision. Section 170 does not create an offence and carries no punishment of its own. It is a limited, preventive power, and it is tied to the immediate prevention of a specific cognizable offence, not to investigation or punishment.
Prevention, not investigation
A Section 170 arrest is justified only to stop a cognizable offence that cannot otherwise be prevented. It is not a shortcut to detain a person for questioning or to build a case. If detention is to continue, it must be authorised under some other provision of law.
03Old to new: CrPC 151 becomes BNSS 170
The power corresponds directly to the old CrPC 151, and the wording is nearly identical.
| Subject | Old (CrPC, 1973) | New (BNSS, 2023) |
|---|---|---|
| Preventive arrest power | Section 151(1) | Section 170(1) |
| 24-hour detention cap | Section 151(2) | Section 170(2) |
The preventive arrest power has been substantially retained. For the general law on arrest under the new code, see arrest under Section 35 BNSS.
04The conditions that must be met
The power is read narrowly, and every word of the condition matters.
- Knowledge of a design. The officer must know of a plan or design to commit a cognizable offence. A vague suspicion is not enough.
- A cognizable offence. The offence feared must be a cognizable one. The power does not extend to non-cognizable matters.
- No other way to prevent it. The arrest is allowed only if it appears that the offence cannot otherwise be prevented. If a lesser step would work, the arrest is not justified.
Because the conditions are strict, a preventive arrest that does not meet them can be challenged as unlawful.
05The 24-hour limit and other safeguards
The most important safeguard is in sub-section (2). A person arrested under this power cannot be kept in custody for more than 24 hours from the time of arrest, unless further detention is required or authorised under the BNSS or any other law for the time being in force. The old Section 151(2) set the same limit.
Beyond the section itself, the general safeguards on arrest apply. A person must not ordinarily be detained for more than 24 hours without being produced before a Magistrate, in line with Article 22 of the Constitution and the general arrest provisions of the BNSS. Personal liberty can be restricted only through a fair and reasonable procedure. For the bail routes a person may use, see anticipatory bail under Section 482 BNSS and bail under Section 480 BNSS.
06What changed under the BNSS
The substance of the power is carried over with little change from the old Section 151, including the 24-hour cap. The main shift is in context rather than text: the new code is read with its modern procedural safeguards, and courts continue to stress that preventive arrest must be genuinely necessary and not a routine step.
Commentary names earlier Supreme Court rulings on custody and liberty as relevant to how this power is used. Those judgments should be read directly before they are relied on in a matter.
07Where Claw fits
Claw is an all-in-one legaltech platform for Indian advocates, law firms, and corporate legal teams, combining AI-based case search, an AI legal assistant (Legal GPT), case management, and compliance automation across all Indian courts and tribunals.
A preventive arrest is usually tested on whether its strict conditions were met, so the first task is to see how courts have read those conditions and the 24-hour cap. Claw lets you search 30 crore+ judgments to trace how benches have applied Section 170 of the BNSS and the old Section 151 of the CrPC, with results in under 5 seconds and coverage from the Supreme Court since 1950 and the High Courts since 1990. It also follows cases, orders and hearings linked to such arrests, by party or advocate name, across 9,102 courts, benches and forums. Claw does not use customer case documents to train AI models.
Create a free Claw account to search and track these matters by party or advocate name. To follow a case across courts, see how to track criminal case hearings and the case search hub.
08Sources and further reading
- India Code (official text of the BNSS, 2023): indiacode.nic.in
- Ministry of Home Affairs (new criminal laws): mha.gov.in
- Claw: clawlaw.in
This explainer is general information, not legal advice. Read the current text of Section 170 and take advice from counsel before relying on it in a case.
09Frequently asked questions
What is Section 170 of the BNSS?
It is the power of preventive arrest. A police officer who knows of a design to commit a cognizable offence may arrest the person, without a warrant, if the offence cannot otherwise be prevented. It replaced Section 151 of the CrPC from 1 July 2024.
Which old section did BNSS 170 replace?
Section 151 of the Code of Criminal Procedure, 1973. The wording, including the 24-hour detention limit, is carried over with little change.
How long can the police hold a person under Section 170?
Not more than 24 hours from the time of arrest, unless further detention is required or authorised under the BNSS or another law. This limit is in sub-section (2).
Can a preventive arrest be challenged?
Yes. The power is narrow. If the officer did not have knowledge of a design to commit a cognizable offence, or if the offence could have been prevented without an arrest, the arrest can be challenged as unlawful.
Is Section 170 an offence?
No. It is a police power to prevent an offence, not an offence itself, so it carries no punishment of its own. Any continued detention must be authorised under some other provision of law.
Can I track cases involving Section 170 in Claw?
Yes. Claw lets you search judgments on Section 170 BNSS and the old Section 151 CrPC across a base of 30 crore+ judgments, with results in under 5 seconds, and track live matters by party or advocate name across 9,102 courts, benches and forums. It does not give legal advice.