A Rationale for the Differential Regulatory Treatment of Imports When Invasive Species are a Potential Problem

The maritime trade related risks from invasive species in a nation depend, inter alia, on the countries from which goods are being imported. In the United States, the USDA's APHIS routinely uses inspections to screen arriving ships at seaports for invasive species. Given this state of affairs, we first use queuing theory to construct a simple model of maritime trade and seaport inspections with one importing nation (Home) and two exporting nations. We then derive a ratio criterion that specifies a condition under which it makes sense for a seaport manager in Home to grant favorable regulatory treatment to the imports from one or the other exporting country. This country of origin rule depends on the mean time it takes to inspect ships from the two exporting countries and on the dollar value of the imports from these two countries