law: 45. Power to make Statutes or Ordinances or Regulations retrospectively.-
  The power to make Statutes or Ordinances or Regulations under section 41 or section 42 or section 43, as the case may be, shall include the power to give retrospective effect, from a date not earlier than the date of commencement of this Act, to the Statutes or Ordinances or Regulations or any of them but no retrospective effect shall be given to any Statutes or Ordinances or Regulations so as to prejudicially affect the interests of any person to whom such Statutes or Ordinances or Regulations may be applicable.