A new draft revised version of Chapter 9 of the Tri-Council Policy Statement addresses that problem. While it calls for researchers to secure the permission of Aboriginal governments for most types of research, it recognizes that this may be inappropriate when those governments themselves are being critically examined:
Article 9.7. Research that critically examines the conduct of public institutions or persons in authority may do so ethically, notwithstanding the usual requirement, in research involving Aboriginal peoples, of engaging representative leaders.
As I have written before, the draft TCPS is inconsistent in its respect for critical inquiry, and ethics committees may not give sufficient weight to the disclaimers like this one. But such statements do give researchers a foothold in arguing for the freedom of inquiry.