The perception that biosecurity import restrictions are used as disguised barriers to trade is widespread. Despite this perception, there has been little empirical analysis distinguishing genuine attempts to protect against introductions of foreign pests and diseases from attempts to distort trade. In this dissertation, I examine the extent to which enforcement of a biosecurity import standard - US agricultural border inspections for non-indigenous species (NIS) - is used as a disguised barrier to trade. I develop a theoretical model of border inspections that incorporates incentives to protect domestic agricultural producers from import competition as well as incentives to protect against NIS damage associated with agricultural imports. The theoretical model is used to specify an econometric model of border inspection that identifies a parameter representing the implied weight the inspection agency places on domestic producer welfare relative to consumer welfare. The structural model further identifies a parameter representing expected NIS damage as implied by the inspection agency's choice of inspection intensity. I estimate the parameters of the model using a dataset that documents the outcome of US agricultural border inspections.

I find evidence suggesting that the inspection agency places greater weight on domestic producer welfare relative to consumer welfare, independent of expected NIS damage. Estimates of the implicit weight on domestic producer surplus range from 1 to 1.63. These results suggest that inspection protocols are implemented in a trade distorting manner to the benefit of domestic producers and at the expense of domestic consumers. I also find evidence that border inspections are influenced by terms of trade motives. The evidence that inspections are not implemented in a least trade distorting manner is independent of expected NIS damage. A second outcome of the econometric analysis is an estimate of expected NIS damage: I find that the inspection agency behaves as if expected NIS damage ranges from $0 to more than $0.25 per dollar of inspected imports.