Recall Rousseau, that terrible proto-totalitarian whom Pettit is at serious pains to distance himself from despite his centrality to the republican tradition. Rousseau is insistent that sovereignty cannot be divided, that the people must be sovereign and that that means that there must be no other powers entitled to limit its lawmaking power. This is because, as he puts it
If the law doesn't govern everything, then it doesn't solve the coordination problem of getting out of the state of nature and its attendant violence and unpleasantness. More, the members of the sovereign wouldn't be free, since they wouldn't be obeyed laws they had made. Some of the rules they obeyed would be set by the rights retained from the state of nature, which they did not set. Of course, many of the rules they will set are exactly those rules that are supposed to govern our interactions in the state of nature; the reasons for thinking we ought not to be entitled to chop off each others limbs as we please are much the same whether or not we have a government, after all. Still, when they *set* them, they are theirs and so they are not bound by rules that are not theirs.“if individuals were left some rights… each, being judge in his own case on some issue, would soon claim to be so on all, the state of nature would subsist and the association necessarily become tyrannical or empty” (Social Contract, 1.6.7)
Pettit's contestatory democracy, of course, consists of putting limits on the people's legislative power. He explains this, in a 1999 piece entitled Republican Freedom and Contestatory Democratization, by arguing that the people as a collective are not the same as the people as a set of individuals. Fair enough; what we collectively will may not be what we all individually will, although one way of interpreting Rousseau is see him as saying that if we don't all individually will, at least in some sense, what we collectively will, then the possibility of decent, non-oppressive government is already gone, precisely because some of us are now living under laws we didn't will. What's interesting about Pettit's contestatory democracy is that he thinks giving everyone opportunities to try and exempt themselves from the general will solves this problem.
All that does, though, is ensure that rather than the will of the democratic majority deciding the law, the will of some minority capable of mobilising the support of members of the political and social elite will decide the law. Pettit thinks this somehow involves the exercise of less arbitrary power than if majorities get what they want, as if giving one actor a power does not exclude another from having it. It's not an accident, it strikes me, that he has had to issue a culpa mea for failing to see how banks might be a bit of a problem for republicans when he takes his cues from people whose main concern, beyond the association between standing armies and despotism, seems to have been to prevent "improper and wicked projects" like the "an equal division of property" or the "abolition of debts". The question is, he has forgotten, if he ever knew, who coerces whom, and if it's not us, it'll certainly be them.