The criminal justice system in India is based on the Criminal Procedure Code (CrPC), which was passed in 1973. It goes into great depth about the process of looking into criminal matters, tracking down offenders, holding trials in criminal courts, and punishing those found guilty. The CrPC has undergone multiple revisions in the past to accommodate changing societal demands and legal obligations.

First enacted in 1861, it underwent several revisions, the most notable of which occurred in 1973 in response to the First and Fifth Law Commissions' recommendations. The Criminal Procedure Code (CrPC) has faced criticism for its extensive reach, citing problems such excessive incarceration rates, pervasive corruption, and the capricious exercise of discretionary powers, especially in relation to Section 144.

A paradigm shift in the procedural components of criminal justice is brought about by the Bharatiya Nyaya Sanhita (BNSS), which introduces significant amendments to the CrPC. The BNSS suggests certain changes meant to modernise and streamline the criminal justice system, while keeping the fundamental framework of the CrPC.

These adjustments aim to improve the system's efficiency and equity while addressing current legal issues. The growth of legal and forensic sciences, along with modern necessities, have led to a substantial evolution of the Criminal Procedure Code, which is reflected in the BNSS. The Indian criminal justice system's efficiency, equity, and accessibility are to be improved by the BNSS through the incorporation of new provisions and the extension of current ones.

1. Undertrial detention: In accordance with the CrPC, an accused individual shall be freed on a personal bond after serving half of the allotted time in custody, with the exception of crimes carrying a death penalty. The BNSS further states that this clause will not apply to (i) crimes carrying a life sentence and (ii) individuals who are the subject of ongoing legal proceedings for multiple offences.
    
2. Medical examination: Under the CrPC, if a sub-inspector level police officer requests it, a registered medical practitioner may do a medical examination of the accused in certain circumstances, including rape. Any police officer may seek such an examination under the BNSS.
    
3. Forensic investigation: For offences carrying a minimum sentence of seven years in prison, the BNSS requires forensic inquiry. In these situations, forensic specialists are required to go to crime sites in order to gather forensic evidence and document the proceedings using a cell phone or other electronic gadget. A state must use facilities in another state if it does not have forensic facilities.
    
4. Finger impressions and signatures: A magistrate may require someone to produce sample handwriting or signatures under the CrPC. This is expanded by the BNSS to allow collection from people who are not in custody and includes voice samples and finger impressions.
    
5. Procedure timelines: The BNSS establishes deadlines for a number of different procedures. For instance, it mandates that physicians who treat rape victims provide the investigating officer with their reports within seven days of the examination. Other deadlines include:
   1. rendering a decision within 30 days of the conclusion of the arguments (with a 60-day extension possible);
   2. notifying the victim of the investigation's advancement within 90 days.
       
6. Court System: The Criminal Procedure Code (CrPC) delineates a judicial system in India for criminal cases. This system comprises Magistrate's Courts, Sessions Courts, High Courts, and the Supreme Court. It gives state governments the authority to designate any town or city with a population of one million or more as a metropolitan area and to designate Metropolitan Magistrates for these areas. This clause is absent from the BNSS.