Under the Immigration & Nationality Act’s Visa Waiver Program, citizens of thirty-eight, mostly European, countries can enter the United States without having to apply for a visa for trips of 90 days or less. The program was restricted in December of 2015, when Congress passed the provisions of H.R. 158 by adding them to a $1.1 trillion spending bill, the “Consolidated Appropriations Act, 2016” intended to keep government services funded through September 2016.
The new restrictions state that if any of the citizens of those thirty-eight states are also nationals of Iran, Sudan, Iraq and Syria, they must now apply for an entry visa to the U.S. In addition, anyone who has visited Iran, Sudan, Iraq and Syria since March 1, 2011 must also apply for a visa, even if they are not nationals of those countries. There are exceptions made for such visitors, say for government service, on a case by case basis. More information can be found at https://esta.cbp.dhs.gov/esta/.
On February 18, 2016, Libya, Somalia and Yemen were added to the list of countries affected by the new restrictions. However, only visitors to, not dual nationals of, Libya, Somalia and Yemen must apply for visas.
Some U.S. citizens are now concerned that because the visa waiver program works on reciprocity between nations, Europe will begin to impose similar restrictions on citizens of the U.S. There are a variety groups, such as the ACLU and the American Immigration Lawyers Association, who have voiced strong opposition to these restrictions and continue to lobby for reform.