Can a person who complains about a drug-related crime also investigate the crime?

In India, narcotic drugs like charas (hemp), ganja, opium etc. are regulated by the Narcotic Drugs and Psychotropic Substances Act, 1985 (NDPS Act). The Act punishes the manufacture, possession, sale and use of these drugs.

In a judgement today, the Supreme Court discussed a situation where a person who files a complaint (complainant) under the NDPS Act also takes charge of investigating the complaint. The Court said that just because the complainant is the same as the Investigating Officer, this does not mean that the investigation is biased. The same person who gives information about the NDPS crime and files a complaint, can then take charge of the criminal investigation. This does not destroy the legal validity of the criminal trial process.

The Supreme Court clarified that just because the informant and Investigating Officer are the same person, the Court cannot assume that the investigation has been corrupted. The Court will have to decide whether the investigation process has been harmed only after looking into the facts and circumstances of a case.

Previously, in Mukesh Singh v. State, the Supreme Court had said that in a case where the complainant himself conducts the investigation, this aspect of the matter can certainly be given weightage while assessing the evidence. However, it cannot be said that just because the complainant and Investigating Officer are the same, the legal validity of the trial itself is destroyed. A person accused of committing an offence under the NDPS Act cannot be acquitted (held to be not guilty) by the Court merely based on the fact that the person who filed the complaint is also the Investigating Officer.