I don't have the exact wording of the motion in front of me, but I think I have a general sense of it.
My understanding of the subamendment and the motion more generally is that, in effect, it is not, as I understand it, a protection against constitutional challenges, because it is an amendment to proposed section 718.4 itself and proposed subsection 718.4(1). Proposed subsection 718.4(1) is a sentencing provision that would allow a judge, in respect of a specific offender, to depart from the imposition of an MMP if it would be cruel and unusual with respect to that offender. My understanding is that proposed subsection 718.4(1.1) would not preclude the ability of an individual accused to launch a constitutional challenge to an MMP under section 12.
My understanding of amendment CPC-23 is that it is very much constrained to the architecture that is proposed in Bill C-16 around the safety valve and the ability to depart from the MMP in a particular case.