Chris W. Bonneau and Damon M. Cann (2011). Campaign Spending, Diminishing Marginal Returns, and Campaign Finance Restrictions in Judicial Elections. The Journal of Politics, 73 , 1267-1280
“Candidate spending in judicial elections has diminishing marginal returns, but that the returns to challenger spending diminish more slowly than incumbent spending.”
“The effectiveness of each additional unit of candidate spending decreases clearly for both incumbents and challengers.”
“Increasing spending at low levels (from $100,000 of spending to $200,000 of spending) improves the spender’s vote share; that specific increase for an incumbent increases incumbent vote share by 0.99% while that level of spending by a challenger decreases incumbent vote share by 2.15%. In contrast, increasing spending from $500,000 to $600,000 for an incumbent increases incumbent vote share by only 0.22%; the same increase in spending for a challenger decreases incumbent vote share by 0.24%.”
For years, scholars of elections have argued about whether campaign finance limitations adversely affect electoral competition. In this article, we examine how the institutional campaign finance restrictions differentially affect the performance of incumbents and challengers. Using elections for the state high court bench between 1990 and 2004, we demonstrate that candidate spending in judicial elections has diminishing marginal returns, but that the returns to challenger spending diminish more slowly than incumbent spending. Since this is the case, campaign finance restrictions that limit candidate spending disproportionately harm challengers, increasing the incumbency advantage and decreasing electoral competition. More specifically, we show that states with more stringent contribution limits have lower levels of candidate spending, and these restrictions thus put challengers at a competitive disadvantage.