In the course of preparing for my oral argument in San Diego in the challenge to five of its contribution limitations, I had the chance to read closely the dissenting opinion of Judge Michael in the Fourth Circuit case, North Carolina Right to Life v. Leake.
I was struck by the following discussion there of a constitutional argument for limiting contributions to independent expenditure committees, coming out of testimony presented to the trial court, and think it could provide the basis for constructing a strong anti-extortion rationale for some of these limits. (The discussion begins on p. 93 of the slip opinion):

The campaign waged in North Carolina by the independent group Farmers for Fairness (Farmers) provides another example of the corruptive influence of independent expenditures. Farmers created advertisements directly opposing certain legislative candidates. Instead of simply running the advertisements during election time, Farmers scheduled meetings with legislators and screened the advertisements for them in private. Farmers then explained that, unless the legislators supported its positions, it would run the advertisements that attacked the candidates on positions unrelated to those advocated by Farmers. The majority interprets this activity as the “group feel[ing] passionately about an issue and discuss[ing] it.” Ante at 30. This could not be further from reality. The record reveals that Farmers did not discuss its central issue, deregulation of the hog industry, in its advertisements. Instead, it threatened and coerced candidates to adopt its position, and, if the candidate refused, ran negative advertisements having no connection with the position it advocated. This activity is not “pure political speech,” ante at 46; it is an attempt to use pooled money for behind-the-scenes coercion of elected officials. The majority also opines that inasmuch as Farmers discussed its intention to run the advertisements with the candidates, their activities were coordinated. Ante at 30-31. This is simply wrong. A threat cannot qualify as coordination because the targeted candidate would not be willingly cooperating if he or she chose to surrender to the demands of the Farmers group. If the candidate chose not to surrender, and Farmers then made good on its threat to broadcast negative advertisements, it is equally clear that the candidate would not have directed or otherwise cooperated with the airing of the advertisement. The Farmers example shows exactly how independent expenditures can create the same appearance of corruption and potential for actual corruption as do excessively large contributions. The only difference between these two methods (other than, after today’s decision, that one may be regulated and the other may not) is that the independent expenditures made by Farmers had the potential to influence candidates through threats and reprisals, while excessively large direct contributions have the potential to influence candidates by rendering them beholden to the donor. In short, the method may differ, but the corrosive effect on the electoral process remains the same.
These examples are certainly not exhaustive. The record contains hundreds of pages of testimony and reports supporting the judgment of the North Carolina legislature that independent expenditure political committees are sufficiently harmful to the electoral process to justify the $4000 contribution limit.11 All of these examples show that North Carolina has an important interest in limiting the corruption or appearance of corruption that can stem from large contributions to independent committees with significant informal ties to coordinated committees, political parties, and candidates. The evidence shows that independent expenditures can have a large “potential impact on a candidate’s election,” and are of great “value to the candidate,” even if the committee does not take any direction from a candidate. See McConnell, 540 U.S. at 152.

I’ll be thinking about this issue some more in coming days, but I think it is a brilliant observation by Judge Michael and potentially a new way to think about the constitutional questions.