I am going to reference only the UNDRIP, the United Nations Declaration on the Rights of Indigenous Peoples. Interestingly, and I don't have time to get into it, there is a whole level of autonomy and self-governance, and a lot of models. It's one thing to say to respect it, but then that also allows first nations and aboriginal communities...who may define things like sex work or prostitution much differently than Canadian law does. So I doubt that the committee would necessarily want to include that. However, there are actual international obligations, as a signatory to it, to actually be in compliance with it. I don't think dropping it into the preamble necessarily means you are complying.
On July 10th, 2014. See this statement in context.