Retrospective or prospective date for implementation of law

PC Act has been modified which has created a problem for us. Number of charge sheets are in the court and number of cases are pending with us for investigation in which public servants are to be enquired. Please guide me whether under this new law we have to seek approval from competent authority to enquire in to the matter or considering the registration of case much prior to the date of new PC Act I may proceed as per old act in which we do not need any approval from competent authority.