Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
We analyze special interest influence on policy when political contributions are capped but the regulation contains soft‐money loopholes. The politician chooses between two policy options. We define special interest influence as the probability the politician chooses the policy he would not have chosen in the absence of contributions. Any binding cap reduces special interest influence but the effect may be nonmonotonic. A ban on contributions can result in greater special interest influence than a binding but nonzero cap. The results may also have implications for the policy response to the 2010 Supreme Court ruling on Citizens United v. FEC.