Case diary is the daily record maintained by a police officer during the investigation of a criminal case, documenting every step of the investigation including the time, place, and manner of investigative actions, the circumstances ascertained, and the statements recorded. Under Indian law, the maintenance of a case diary is mandatory under Section 172 of the Code of Criminal Procedure, 1973 (CrPC), now replaced by Section 193 of the Bharatiya Nagarik Suraksha Sanhita, 2023 (BNSS).
Legal definition
Section 172 of the Code of Criminal Procedure, 1973 provides:
Section 172(1): Every police officer making an investigation under this Chapter shall day by day enter his proceedings in the investigation in a diary, setting forth the time at which the information reached him, the time at which he began and closed his investigation, the place or places visited by him, and a statement of the circumstances ascertained through his investigation.
Section 172(2): Any Criminal Court may send for the police diaries of a case under inquiry or trial in such Court, and may use such diaries, not as evidence in the case, but to aid it in such inquiry or trial.
Section 172(3): Neither the accused nor his agents shall be entitled to call for such diaries, nor shall he or they be entitled to see them merely because they are referred to by the Court; but, if they are used by the police officer who made them to refresh his memory, or if the Court uses them for the purpose of contradicting such police officer, the provisions of section 161 or section 145, as the case may be, of the Indian Evidence Act, 1872, shall apply.
New law equivalent: Section 193 of the Bharatiya Nagarik Suraksha Sanhita, 2023 (BNSS) substantially reproduces Section 172 CrPC, with the added provision that the case diary may be maintained in electronic form in the manner prescribed by the State Government.
How courts have interpreted this term
State of Karnataka v. Yarappa Reddy [(1999) 8 SCC 715]
The Supreme Court held that the case diary is a contemporaneous record of the investigation and serves as a check on the conduct of the investigating officer. The Court emphasised that the diary must be maintained faithfully and regularly — any gap or interpolation in the case diary raises an adverse inference regarding the integrity of the investigation.
Sidhartha Vashisht @ Manu Sharma v. State (NCT of Delhi) [(2010) 6 SCC 1]
In the Jessica Lal murder case, the Supreme Court examined the case diary to identify deficiencies in the investigation. The Court held that case diaries can be relied upon by the court to verify the thoroughness of the investigation and to identify whether the investigating officer failed to follow up on material leads.
Shamshul Kanwar v. State of U.P. [(1995) 4 SCC 430]
The Supreme Court reiterated that the case diary is not evidence in the case — it can only be used by the court as an aid in the inquiry or trial. It cannot be used by the accused or their agents except in the limited circumstances provided under Section 172(3).
Why this matters
The case diary is the backbone of every criminal investigation in India. It provides a contemporaneous, day-by-day record of what the investigating officer did, when, where, and what was found. For the criminal justice system, it serves as both an accountability mechanism and an investigative tool — the court can examine the diary to assess whether the investigation was conducted thoroughly, honestly, and in accordance with law.
For defence practitioners, the case diary is both accessible and restricted. The accused has no right to see the case diary merely because the court refers to it. However, when the investigating officer uses the diary to refresh memory during testimony, the defence can demand to see the specific entries under Section 161 of the Indian Evidence Act, 1872 (now Bharatiya Sakshya Adhiniyam, 2023). This creates a tactical window during cross-examination to challenge the investigating officer's testimony.
The BNSS amendment allowing electronic case diaries represents a significant modernisation. Electronic diaries are harder to tamper with (due to metadata and audit trails), can be accessed more efficiently by courts, and facilitate oversight by superior officers. However, the practical implementation depends on the technological infrastructure available to police stations across India.
Related terms
Related concepts:
Related procedural concepts:
Frequently asked questions
Can the accused see the case diary?
No, not as a matter of right. Under Section 172(3) CrPC (Section 193(3) BNSS), the accused and their agents are not entitled to call for or see the case diary merely because the court refers to it. However, if the police officer uses the diary to refresh memory during testimony, the accused can demand to see those specific entries under the provisions of the Evidence Act.
Is the case diary admissible as evidence?
No. Section 172(2) CrPC (Section 193(2) BNSS) expressly provides that the case diary may be used by the court "not as evidence in the case, but to aid it in such inquiry or trial." The case diary is an aid to the court, not substantive evidence. However, it can be used to contradict the investigating officer's testimony.
What is the difference between a case diary and an FIR?
An FIR (First Information Report) is the first document that sets the criminal law in motion — it records the initial information about a cognisable offence. The case diary is the daily record of the investigation that follows the FIR. The FIR is a public document accessible to the accused; the case diary is a confidential document with restricted access.
This entry is part of the Veritect Indian Legal Glossary, a comprehensive reference of Indian legal terminology grounded in statutory text and judicial interpretation.
Last updated: 2026-03-27. Veritect provides this content for informational purposes and does not constitute legal advice.