In 2009, the High Court of Australia in the Minister for Immigration and Citizenship v SZIZO decided in respect of certain provisions of the Migration Act 1958 (Cth) that ‘Notwithstanding the detailed prescription of the regime’ ‘and the use of imperative language it was an error to conclude that the provisions’ 'are inviolable’. By this judgment, the High Court established two classes of provision under the Migration Act 1958 (Cth): one violable and the other inviolable. Since then, the search has continued in practice to work out which provisions under the Migration Act 1958 (Cth) are violable and which are inviolable. In this article, ss 360A(4) and 425A(3) of the Migration Act 1958 (Cth) concerning the statutory notice period for a hearing in the Migration Review Tribunal and the Refugee Review Tribunal are considered to ascertain whether they are violable or inviolable. The first part of the article deals with natural justice, a key to considering the issue of violability. The author contends that there are two approaches to determining the question of the violability of the statutory provisions arising from the High Court decision. The article then analyses the provisions of the statutory notice period to clarify its scope. Finally, the issue of the violability of the provisions concerning the statutory notice period is examined.