Many have criticized the Mirabel land expropriations of the late 1960s.
Sovereignists, of course, treat this as simply another jug of kerosene to add to the mythical bonfire that must, eventually, destroy the federal government and from which shall rise the phoenix of the Québec "nation".
Objectively, the issue becomes more complex. In the late 1960s, it could arguably be affirmed that Montreal was well on its way to fulfilling a rather lofty destiny as a preeminent metropolis in Canada and North America. History has since conspired to send Toronto along that path, though Montreal remains a vibrant and growing metropolitan area.
Responsible urban planning (i.e. the contrary of what's going on in Ottawa) calls upon municipal architects to foresee the growth needs of an area not in terms of years, but decades. The former Dorval Airport is located notoriously close to the Montreal downtown, and its capacity for expansion is limited.
While expropriation is never a pleasant process, I must quote Spock here by stating that "the needs of the many outweigh the needs of the few", and Kirk, "Or the one". That doesn't change the realities of the many families and communities permanently affected by the loss of their lands and their livelihoods.
The very unfortunate occurence today is that the Conservatives are further twisting this dagger in the collective wounds of quebeckers, affirming that the retrocession of Mirabel lands consists of the restoration of past injustices, when it smacks much more evidently of crass politicking in light of upcoming federal elections.
The Conservatives are depriving the area of the leverage to develop the Mirabel Airport, which of course, in the eyes of anyone with any inkling of foresight, will eventually reopen and eclipse the current Trudeau Airport in a matter of a couple decades. This is inevitable, and even, desirable, should the greater Montreal area achieve its full development potential.
Mirabel was not a mistake. It was killed by virtue of a succession of political backfiring, mismanagement and underinvestment. Dorval should have been killed upon the opening of Dorval. The autoroutes 13 and 50 should have been completed, and the high-speed rail link should have been completed. Only upon the fulfillment of these conditions would the viability of Mirabel become unavoidably evident - and of course, save the public purse hundreds of millions of dollars in correcting past mistakes and hesitations.