For the first 100-odd years of our Confederation, we did not have a Charter of Rights and Freedoms in its current form. Two important rights in there are section 3, the right to vote, and section 15, the right to equality.
The first cases evaluating the effect of those new charter provisions on aspects of our electoral system—probably one of the earliest—was the 1986 Dixon case here in B.C. assessing the constitutionality of variations in riding size. At the time, there was a 15-fold difference between the northwest district that included Atlin and a riding in Surrey. Justice McLachlin ruled that was unconstitutional according to the charter, so there's now judgment language, precedent, around the importance of voter parity.
Actually, equality of voting power is only to be disrupted or attenuated in order to provide more effective representation. You've heard a ton of testimony that says that many people are much less effectively represented by our current system, so in our view that can't be countenance.