Citizens United, States Divided: An Empirical Analysis of Independent Political Spending

58 Pages Posted: 28 Apr 2012 Last revised: 22 Jan 2014

Douglas M. Spencer

University of Connecticut, School of Law

Abby K. Wood

USC Gould School of Law

Date Written: April 14, 2012


What effect has Citizens United v. FEC had on independent spending in American politics? Previous attempts to answer this question have focused solely on federal elections where there is no baseline for comparing changes in spending behavior. We overcome this limitation by examining the effects of Citizens United as a natural experiment on the states. Before Citizens United about half of the states banned corporate independent expenditures and thus were “treated” by the Supreme Court’s decision, which invalidated these state laws. We rely on recently released state-level data to compare spending in “treated” states to spending in the “control” states that have never banned corporate or union independent expenditures. We find that while independent expenditures increased in both treated and control states between 2006 and 2010, the increase was more than twice as large in the treated states and nearly all of the new money was funneled through nonprofit organizations and political committees where weak disclosure laws and practices protected the anonymity of the spenders. Finally, we observe that the increase in spending after Citizens United was not the product of fewer, larger expenditures as many scholars and pundits predicted, and we note that people were just as likely to make smaller expenditures (less than $400) after Citizens United as they were before. This finding is particularly striking because it cuts against the conventional wisdom of spending behavior and also challenges the logic of those who disagree with the most controversial element of the Citizens United decision – the rejection of political equality as a valid state interest.

Keywords: Campaign finance, election law, independent expenditures, political equality, Super PAC, difference-in-differences, quantile regression

Suggested Citation

Spencer, Douglas M. and Wood, Abby K., Citizens United, States Divided: An Empirical Analysis of Independent Political Spending (April 14, 2012). Indiana Law Journal, Vol. 89, No. 1, pp. 315-372 (2014). Available at SSRN: or

Douglas M. Spencer (Contact Author)

University of Connecticut, School of Law ( email )

65 Elizabeth Street
Hartford, CT 06105
United States

Abby K. Wood

USC Gould School of Law ( email )

699 Exposition Boulevard
Los Angeles, CA 90089
United States


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