From the summary:
Following the Supreme Court’s January 21, 2010, ruling in Citizens United v. Federal Election Commission, questions have emerged about which policy options could be available to Congress. This report provides an overview of selected campaign finance policy options that may be relevant. It also briefly comments on how Citizens United might affect political advertising. A complete understanding of how Citizens United will affect the campaign and policy environments is likely to be unavailable until at least the conclusion of the 2010 election cycle.
If Congress pursues additional legislation, at least two broad choices could be relevant. First, Congress could provide candidates or parties with additional access to funds to combat corporate influence in elections. Second, Congress could restrict spending under certain conditions or require those making expenditures post-Citizens United to provide additional information to voters or regulators. Options within both approaches could generate substantial debate. Some may contend that the only way to provide Congress with the power to directly affect the content of the ruling would be to amend the Constitution.
Bills introduced as of this writing that may be relevant for legislative responses to Citizens United include, but are not necessarily limited to H.J.Res. 13, H.J.Res. 68, H.R. 158, H.R. 1826, H.R. 2056, H.R. 3859, H.R. 4487,H.R. 4511, H.R. 4517, H.R. 4522, H.R. 4523, H.R. 4527, H.R. 4537, H.R. 4540, S. 752, S. 2954, and S. 2959. Given the pace of developments since the ruling, this report is not intended to be exhaustive. Relevant legislation that has been introduced thus far is reflected through selected examples. Additional legislation will be included in future updates. This report is not intended to provide a legal analysis of Citizens United or of legal issues that might affect the policy options discussed here. CRS Report R41045, The Constitutionality of Regulating Corporate Expenditures: A Brief Analysis of the Supreme Court Ruling in Citizens United v. FEC, by L. Paige Whitaker discusses legal aspects of the decision.
Life After Citizens United
Source: National Conference of State Legislatures, February 18, 2010