(b) for the imposition of restrictions on the movement or residence within Saint Lucia or on the right to leave Saint Lucia of persons generally or any class of persons in the interests of defence, public safety, public order, public morality or public health or, in respect of the right to leave Saint Lucia, of securing compliance with any international obligation of the Government particulars of which have been laid before the Senate and the House and except so far as that provision or, as the case may be, the thing done under the authority thereof is shown not to be reasonably justifiable in a democratic society;