The principle that a person should be presumed innocent until proven guilty is a fundamental principle of procedural fairness in criminal law. Its justifications lie in the socio-legal consequences of convicting an individual for the commission of a crime. This principle acts as a protection against erroneous convictions and ensures that an accused is not oppressed by the immense power and resources of the State. The opposite rule – a presumption of guilt – imposes an unfair burden on the accused that requires him to prove his innocence, failing which he is convicted. Such a burden is envisaged by reverse onus clauses or reverse burdens, which supplant the hallowed presumption of innocence with the grossly unjust presumption of guilt. This paper argues that reverse onus clauses are both unconstitutional and a glaring contravention of a sacred principle of criminal law.