Section 30

Where for the purpose of the prosecution of any person for an offence under this Act by reason of his failure to comply with the notification to present himself for national service training under subsection 17(2) it is necessary to show that he is or was at any particular time liable to present himself for national service training or that he is or was within particular limits of age, he shall be presumed to be, or to have been, at that time so liable or within those limits of age, unless the contrary is proved.