Narcotic Drugs and Psychotropic Substances Act, 1985 ~ ss. 18, 35, 42, 43 and 57 — Prosecution u/s. 18 r/w. ss. 457 and 380 of Penal Code — For theft of opium and possession thereof — Recovery of the contraband at the instance of the accused from a public place where he had concealed the same — Conviction by courts below — On appeal, pleas of accused that the Act was not applicable since the offence was committed before enforcement thereof, that conviction under the Act would tantamount to retrospective operation which is against Art. 20(1) of the Constitution; that conviction is vitiated for non-compliance of ss. 42(2) and 57; that disclosure statement of the accused not admissible since it was made while the accused was in police custody in connection with another case; and that there was delay in sending the seized articles for chemical examination — Held: The Act is applicable in the present case because, the accused remained in possession of the contraband substance even when the Act came into force — Thus was rightly convicted u/s. 18 — Therefore, it cannot be said that acts of possession was made punishable with retrospective affect, hence violation of Art. 20(1) would not arise — In the present case, since the contraband substance was recovered from a public place, s. 43 would be applicable and not s. 42(2) — Evidence of the case show that there was substantial