The doctrine of reciprocity means that the visa policies applied to foreign nationals entering the U.S. would mirror the policies those foreign nations apply to U.S. citizens. If a country imposes strict visa requirements on Americans, the U.S. would respond by imposing similar restrictions on citizens of that country. This promotes diplomatic leverage, and in a perfect world, could result in better treatment of Americans traveling abroad while they’re in those countries, assuming we’ve agreed to treat visitors from that particular country well while they’re guests of the United States.

In reality, however, some countries would automatically be excluded due to their policies, making enforced reciprocity a means of legally discriminating against foreign visitors from those countries. Israel’s border policy¹⁵ is one such example.

The GOP backed off from its allegiance to reciprocity after WW2, once it was widely recognized that their high tariff policies had worsened the Great Depression¹⁷ and sparked trade wars¹⁸. Now they’re revisiting these misguided and harmful policies even though history has foretold the results.

Full contextual analysis of Section 2.3: Department of State here.