It was simply one of the arguments raised by Key Mail Canada and Spring Canada when they appeared before the court. They said that the English version of the Canada Post Corporation Act was different.
According to the English version, the perception was that they in fact were entitled to do it without any amendment being made to the Canada Post Corporation Act. The judges said no. They found that the two versions were official versions and that, in their view, the two versions were equivalent and they had no right to do it. It was somewhat in those circumstances.