To students of the Supreme Court’s “law of democracy” jurisprudence, there usually seems to be something distressingly inconsistent in the ways in which the Court approached the issue of discrimination against smaller political parties in Figueroa v. Canada (Attorney General), 2003 SCC 37, 1 S.C.R. 912, and that of the silencing of “third parties” in Harper v. Canada (Attorney General), 2004 SCC 33,  1 S.C.R. 827. The former struck down the requirement that a party present at least 50 candidates at an election to benefit from a number of advantages, notably tax-deductibility of donations to it. The latter upheld very severe restrictions on the ability of “third parties” ― that is, persons who were neither parties nor candidates ― to advertise during an election campaign.
As, for example, Michael Pal explains, in Figueroa
the Court’s s. 1 analysis was extremely skeptical, and diverged from the reasoning by the Harper …. majorit[y]. The regulation of political parties in the fashion adopted by Parliament was no less of a “political choice” than the law governing third parties in Harper … The 50-candidate threshold also engaged the same kind of policy-making role for Parliament in balancing where to draw the appropriate line that led the majority in Harper to defer to the specific cap set on third party spending. … Yet the Figueroa majority persisted in a searching examination under s. 1, because it was the role of the Court to ensure meaningful participation in the electoral process. (10)
But perhaps the two decisions are actually less inconsistent than we tend to assume. A re-reading of Figueroa shows that some of the ideas which caused the Supreme Court to adopt a deferential posture in Harper were already present there.
The first is the belief that political parties are the principal means by which citizens make their ideas heard in the political process. Justice Iacobucci, for the majority, claimed that
political parties have a much greater capacity than any one citizen to participate in the open debate that the electoral process engenders. By doing so in a representative capacity, on behalf of their members and supporters, political parties act as a vehicle for the participation of individual citizens in the political life of the country. Political parties ensure that the ideas and opinions of their members and supporters are effectively represented in the open debate occasioned by the electoral process. 
In Figueroa, this belief in the centrality of the parties to pre-electoral debate led the majority to insist that all parties be allowed to compete equally ― among themselves. But in Harper, where the issue was the participation of persons and entities other than parties, the same belief not illogically led the majority to consider their participation as less deserving of protection. Indeed, the majority pointed out that
as the Court discussed in Figueroa, there are few obstacles for individuals to join existing political parties or to create their own parties to facilitate individual participation in elections. Still, some will participate outside the party affiliations. [113; emphasis mine]
For the majority, participation “outside the party affiliations” clearly seems anomalous.
The second idea which was first expressed in Figueroa but then became much more important in Harper is that pre-electoral debate is a zero-sum game; that one person’s or group’s ability to express his or its views as part of that debate effectively comes at the expense of the ability of others to do the same. In Figueroa, the majority took the position
that there is only so much space for political discourse; if one person “yells” or occupies a disproportionate amount of space in the marketplace for ideas, it becomes increasingly difficult for other persons to participate in that discourse. It is possible, in other words, that the voices of certain citizens will be drowned out by the voices of those with a greater capacity to communicate their ideas and opinions to the general public. 
This view is key to Harper where, combined with the belief in the centrality of political parties to pre-electoral debate, it led the majority to conclude ― with reference to the passage just quoted ― that
[i]f a few groups are able to flood the electoral discourse with their message, it is possible, indeed likely, that the voices of some will be drowned out … Where those having access to the most resources monopolize the election discourse, their opponents will be deprived of a reasonable opportunity to speak and be heard. This unequal dissemination of points of view undermines the voter’s ability to be adequately informed of all views. 
And this, in turn, prompted the majority’s holding that not only was it permissible to limit the amounts “third parties” would be allowed to spend in pre-electoral debate, but that these limits could be very low, to avoid all danger of “drowning out” and ensure the centrality of the parties’ discourse.
Figueroa and Harper thus have more in common than we realize, or like to admit. But although there is method in this jurisprudence, it is still misguided. The parties no longer represent the best way for citizens to participate in pre-electoral debate. Indeed, without going into too much detail here (I may have occasion to do so in the near future), they are no longer very interested in debating policy issues at all. The role of injecting policy into public debate is increasingly shifting to “third parties” ― whether unions, NGOs, social movements, or even individuals. Nor is it at all obvious that pre-electoral debate is a zero-sum affair, and that the “drowning out” which worries the Supreme Court is a real danger.
Now, in Figueroa, neither of these ideas is necessary to the outcome. As prof. Pal points out, the legislation at issue in that case “disadvantaged small parties to such a degree that it can fairly be termed an incumbent protection mechanism insulating the large political parties from competition.” (10) This should have been enough to invalidate it. Incumbent-protection mechanisms that have no redeeming value (and, as the Court concluded, the 50-candidate rule was not rationally connected to any pressing and substantial governmental objective) should be regarded as necessarily contrary to the protection of the right to effectively participate in the political process, which the Court has interpreted section 3 of the Charter as protecting. In Harper, by contrast, the Court’s dubious ideas about the political process are central to its conclusion. If they are abandoned, that conclusion is indefensible.