I said I was going but I had to reply to this.
$1:
The GG has no authority to give royal assent to a bill that violates the constitution.
A mite incorrect. Bills that violate the constitution can be signed -- and then challenged by or with the judiciary. It is down to the courts to decide on the constitutionality of a particular document through the legal system in Canada, as is composed by the experts of the Canadian legal system. Note that the judiciary has changed numerous laws, or their interpretation, to match the Charter of Rights and Freedoms that was incorporated into our repatriated Constitution in 1982, as an example.
Indeed, recognize that laws that violating the Constitution is entirely allowed, on the following conditions:
They must be reasonable in a free and democratic society
They must be prescribed by law
They must be demonstrably justifiedEven if unconstitutional, no decision on such matters can arbitrarily be made by an official -- the second bit, prescribed by law, necessitates any deciding body must be written in regulation or legislation. This means the GG would need legislative power to effectively make any changes to the current system, which he does not.
It's why the Oakes test is so well known -- it is the generic (although not entirely correct) method by which courts make decisions on impugning on constitutional rights. For the record, the constitution is not sacrosanct, and can be changed -- parts of it have been changed independently by the Canadian judiciary. Section 33 even allows for provinces to ignore parts of the constitution as they see fit.
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The involvement of the GG is significantly different, and exists here for reasons that Curtman has not mentioned. Treaties have, in practice, been seen as a direct relationship between them and Canada's sovereign -- that is, our Queen. When we incorporated the Charter in 1982, we included clauses specifically oriented towards maintaining native rights and sovereignty, including specifically laying out the natives as not dealing with the consistently changing cabinet, but with the Crown itself, as embodied by our reigning sovereign. This was to ensure stability of the agreements, given concerns over the populist nature of democracy.
This is statutory and constitutional. Their demands for the GG to be there are relevant, if we look at it from this level of analysis. This is founded on our use of the sovereign as our head of state and the the monarchy as a Canadian institution. The two go hand in hand. Indeed, when the Queen and Chretien went to discuss stagnant land claims, the paperwork was handed to the Queen, who then, after speaking to them, handed it over to the Prime Minister.
... and that line is where things begin to fall apart a bit for the natives to some degree, because there are gray areas to consider.
See, while the monarchy has that special relationship with the natives, the problem is that there are government bodies and regimes set forth to administer them on the sovereign's behalf -- Canadian Aboriginal Law, and the Minister of Aboriginal Affairs and Northern Development. These bodies exist to exert the position of HRH. The GG himself is not empowered to impact the decision making of our government -- he is not the sovereign, only HRH's representative. If she so chooses, he can (and should) attend, but only to the degree that he views is correct -- and in line with Canadian tradition and general policy, the GG in this case is following the choice of HRH elected official (Harper) and his office in not engaging with the natives, undercutting other portions of HRH's government in Canada. Recognize the duty of the GG is largely ceremonial.
The Queen has made her decision, as has the Governor General. Their special relationship in this case does not supersede the perceived authority of the PMO, nor does it properly reflect precedent (as seen with Chretien), and would undercut Canadian authority and sovereignty. Some view the use of a colonial-era body on Canada to enforce demands to be somewhat ironic, given the reasoning behind those demands, as a result.
Hence, they had a right for the GG to be there. That is the law. The decision of the sovereign has been to disengage and leave it to the people, and via that special relationship, the FN have to live with that decision. The GG as HRH's representative has decided to follow tradition, and follow the recommendations of the government. It is, however, down to the natives as to whether or not to comply.
So it's a weird position -- the GG should be there, but he wasn't going to have power, nor was the Queen likely to give it to him to act on her behalf. However, the inability for the natives to speak directly to the sovereign to voice their grievances is in stark contrast on centuries old tradition that has been statute and law for much of that time; in fact, it was reaffirmed with the patriation of the constitution in 1982.
Just some thoughts.