Interest groups are a feature of American politics, but studies of their actual effect on issues has been relatively scarce. A 2008 study by the International Monetary Fund, “Do Interest Groups Affect U.S. Immigration Policy?” seeks to quantify if and how different groups influence policy.
The authors developed a model linking migration to the intensity of lobbying activities carried out by pro- and anti-immigration pressure groups and the effects on the number of visas issued. Overall, the study found that interest groups on both sides of the issue play significant roles in shaping migration across sectors. Findings include:
Barriers to immigration are higher in sectors where labor unions are more important. Conversely, barriers are lower in sectors where business lobbies are more active.
A 10% increase in lobbying expenditures by business groups raises the number of visas by between 2.3% and 7.4%.
A 10% increase in union membership rate (assumed to be an effective measure of lobbying expenditures by labor groups) reduces the number of visas by between 2.6% and 10.4%.
The study’s authors also highlight the “visible” and “invisible” restrictions that can be used to manage access to the labor market. “Visible” restrictions take the form of quotas and caps; “invisible” restrictions include rules that regulate entry to selected professions (for example, in the medical sector) or complex employment procedures.