 However, no such statement is admissible or usable if it appears to the court that the making of the statement has been caused by any inducement, threat or promise referring to the charge against that person, proceeding from a person in authority and sufficient, in the court's opinion, to give that person grounds which would appear to him reasonable for supposing that by making it he would gain any advantage or avoid any evil of a temporal nature in reference to the proceedings against him.Notwithstanding anything to the contrary in any written law, a court may order that the whole or any part of any trial before it for any offence under the Act shall be dealt with "in camera" if it is satisfied that it is expedient in the interests of justice or of public safety or security to do so.A police officer or officer of the Central Narcotics Bureau (CNB) may exercise all or any of the following powers in respect of any person under arrest, detained or placed under police supervision under the Act