The Congressional Research Service (CRS) issued report on legislative developments in visa policy over the past 20 years and analysis of statistical trends in visa issuances and grounds for exclusion.
The conventional wisdom is that the terrorist attacks on September 11, 2001, prompted a substantive change in U.S. immigration policy on visa issuances and the grounds for excluding foreign nationals from the United States. A series of laws enacted in the 1990s, however, may have done as much or more to set current U.S. visa policy and the legal grounds for exclusion.
Foreign nationals not already legally residing in the United States who wish to come to the United States generally must obtain a visa to be admitted. Those admitted on a permanent basis are known as immigrants or legal permanent residents (LPRs), while those admitted on a temporary basis are known as nonimmigrants (such as tourists, foreign students, diplomats,temporary agricultural workers, and exchange visitors). They must first meet a set of criteria specified in the Immigration and Nationality Act (INA) that determine whether they are eligible for admission.
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