Interesting thing about Newfoundland and Labrador is that its border with Quebec IS defined by the constitutional amendment that created NL as a province of Canada -- yet the government of Quebec does not officially accept that border and  even occasionally re-draws the map, apparently just to bully the NL government into issuing an official objection.

To an extent, Quebec undermines their own arguments about the value of enshrining anything in the constitution when refusing themselves to respect something so fundamentally constitutional as territory.