Ignorance in Congressional Voting? Evidence from Policy Reversal on the Endangered Species Act

Objective: In 1978 Congress weakened several key provisions of the Endangered Species Act (ESA), which had been enacted only five years earlier. The objective is to compare alternative explanations for this policy reversal. Methods: Probit and multinomial logit models are used to explain empirically how senators voted in both 1973 and 1978, and to investigate why many senators switched their vote from supporting ESA to weakening it. Results: The findings here indicate that party affiliation and policymaker preferences were not important to the 1973 vote, but they were key variables in the 1978 votes and the vote-switching decision. Proxies for unexpected economic impacts of ESA on individual states have little explanatory power. Conclusions: Ignorance, as measured here, does not appear to explain this policy reversal. Rather, an influx of relatively conservative Democrats between 1973 and 1978 presents itself as the leading explanation.