The actual arguments for open borders constitute a strong case. This case can be complemented by taking note of the conclusions that people with expertise on the matter have arrived at. Note that these arguments from authority are only intended to complement the overall case and are not themselves a key part of the case.

In each of the cases listed below, the general observation is that people who know more about relevant subjects, or are in a better position to judge the issues involved, tend to be relatively more supportive of immigration. It is not being claimed here that all, or even most, of these people support complete or near-complete open borders. Thus, it does not provide strong evidence for open borders.

• Economist consensus: Economists, who have relevant expertise that can inform some of the debate on the adverse economic impact of immigration, are generally much more in support of relatively freer migration, both for high-skilled and for low-skilled labor.
• Legal and political scholarly consensus: Immigration scholars in other fields, including legal scholars and political scientists, generally support expanded immigration as well.
• Smart and more informed opinion: Surveys of the public, in countries such as the United States, shows that people with higher IQs, and people who are more informed about the relevant issues, tend to be more supportive of expanded immigration. The findings are relative: in the US context, high IQ people on average support current immigration levels, whereas averae and low IQ people are more likely to support reductions in immigration levels.