13. Statutes which make alterations in procedure regulate secondary rather than primary conduct; they apply to existing proceedings even though these were commenced before the statutes were made and in that sense may be regarded as retrospective. By contrast, there is a presumption that enactments affecting substantive rights are intended to be prospective. This presumption is however a rebuttable one; if it is rebutted, an amendment, though affecting substantive rights, applies retrospectively (barring any impediment of a constitutional nature) and so can affect existing proceedings.

14. Evidence capable of rebutting the presumption is furnished through Rule 6(C), which states that “an amendment shall enter into force immediately, but shall not operate to prejudice the rights of the accused in any pending case”. It is true that a provision stipulating that a statute is to commence at a certain time does not necessarily mean that the statute is to govern previous conduct into which an inquiry is pending at that time. But it depends on the language of the commencement provision. Here there is one commencement provision; it applies to amendments of all kinds. Therefore, every amendment enters into force “immediately”, i.e., whether substantive or procedural, it applies to all cases of which the Tribunal is then or may in future be seised, the sole qualification being that the amendment, of whatever kind, must not “operate to prejudice the rights of the accused in any pending case”. So, the real and only question under the Rules, as they have been crafted, is whether the new amendment to Rule 15bis will operate to prejudice the rights of the Appellants.