The key plank in the argument was legislation that came into force in 2007, the Kyoto Protocol Implementation Act. As s. 3 of the Act explained: "the purpose of this Act is to ensure that Canada takes effective and timely action to meet its obligations under the Kyoto Protocol and help address the problem of global climate change".
Subsequently, however, when Mr. Harper had won a majority in the federal parliament, an order in council was issued authorizing the Minister for Foreign Affairs to take actions necessary to withdraw Canada from the Kyoto Protocol.
There is no doubt that entering into and withdrawing from international agreements is a prerogative power. The first question raised by the applicant was whether the prerogative had been excluded, expressly or by necessary implication, by the Act. No express exclusion could be identified, however, and Noël J. was not persuaded that any exclusion by necessary implication could be identified either:
 Nevertheless, in applying the analysis to the case at bar, this Court is of the opinion that the KPIA contains no provision, condition or restriction that would limit the royal prerogative of the government to withdraw from the Protocol. The applicant relied in particular on the title and purpose of the KPIA: “An Act to ensure Canada meets its global climate change obligations under the Kyoto Protocol [Emphasis added]” and “to ensure that Canada takes effective and timely action to meet its obligations under the Kyoto Protocol [Emphasis added].” However, the government’s decision to withdraw from the Protocol is clearly provided by article 27 of that Protocol and thus the government was in compliance with it.Secondly, the applicant argued that the separation of powers (an unwritten constitutional principle) had been breached by the withdrawal. There are echoes here of the famous House of Lords decision in R. v. Home Secretary, ex parte Fire Brigades Union, where a purported exercise of the prerogative was held to be unlawful because it conflicted with express legislative intent. Here, though, this argument fell with the first: if the Act imposed no express or necessarily implicit restriction on the government's power to withdraw, the separation of powers could not have been violated.
Finally, the applicant relied on an another unwritten constitutional principle, that of democracy: the failure to consult the House of Commons and the provinces before exercising the prerogative was undemocratic. Again, however, because there was no binding legislative restriction placed on the executive, the principle had not been violated.
Another blow then to the unwritten constitutional principles identified by the Supreme Court of Canada in the Secession Reference, overridden not by legislation on this occasion, but by the Royal Prerogative.