NVRI has this wonderful page collecting all the briefs filed in the Vermont spending limits case. I have only had a chance to glance at some of the briefs so far, but I was especially interested to see what the BCRA sponsors were going to say about the constitutionality of spending limits. In this brief (Seth Waxman, counsel of record), Sens. McCain and Feingold, and Reps. Shays and Meehan, ask for more time:

Vermont’s contribution limits are constitutional under longstanding and consistent precedents of this Court. In Buckley v. Valeo, 424 U.S. 1 (1976), this Court upheld a federal $1000 contribution limit. The Court concluded that contribution limits impose only a marginal restriction on speech and are thus subject to less exacting scrutiny than expenditure limits. The Court further concluded that both corruption and the appearance of corruption are constitutionally sufficient justifications to support contribution restrictions. Id. at 26. Within this basic framework, the Court has declined invitations to second-guess legislative judgments that establish particular contribution limits. See, e.g., id. at 30; Nixon v. Shrink Mo. Gov’t PAC, 528 U.S. 377, 391 n.5 (2000); California Med. Ass’n v. Federal Election Comm’n, 453 U.S. 199, 201 (1981) (plurality opinion). This Court rightly refrains from ‘fine tun[ing]’ the precise limits that legislatures adopt based on their experience and expertise and has explained that contribution limits should be upheld unless they are ‘so radical in effect as to render political association ineffective, drive the sound of a candidate’s voice below the level of notice, and render contributions pointless.” Shrink Mo., 528 U.S. at 397.
Applying these well-established standards, the court of appeals correctly upheld Vermont’s contribution limits. The
legislative and trial evidence overwhelmingly demonstrates that those limits are: (1) justified by Vermont’s interest in avoiding actual and apparent corruption; (2) closely drawn to meet that indisputably important interest; and (3) ample enough to allow robust campaigning and debate in Vermont.
This Court should decline at this stage in the litigation to review the constitutionality of Vermont’s expenditure
limits and should reject the invitation to revisit its holding in Buckley concerning expenditure limits. The court of appeals neither sustained nor struck down Vermont’s expenditure limits; instead, it remanded the case to the district court for further fact-finding and analysis regarding whether those limits are narrowly tailored. Those further proceedings may pretermit the need for this Court to engage in constitutional adjudication, which should not be embarked upon unnecessarily or prematurely. If the issue ultimately returns to this Court, the Court will have the considerable benefit of further lower court findings and analysis to inform its decision.
Buckley did not establish a per se constitutional bar on expenditure limits. Rather, it held that any such limit would
need to meet the most exacting scrutiny. This Court should not reconsider that holding and should not assess its application to Act 64 before proceedings in the lower courts have concluded.

Readers of my blog will know that in my view this is exactly the right position. And I remain puzzled why defenders of the Vermont law would have thought it better to push this issue now rather than give the Vermont limits a chance to go into effect, thereby having the chance to demonstrate that the First Amendment costs of the Vermont rule were not too high, and the benefits to Vermont voters and candidates sufficiently large. Even worse from the point of view of reformers, this case gives the new Roberts Court a chance to reverse Shrink Missouri‘s very deferential test for judging whether contribution limits are unconstitutionally low.