Inadmissibility to US / Waiver The immigration laws of the United States prohibit the issuance of a visas and/or admission to the United States to certain noncitizens. Examples of applicants who must be refused visas and admission under the law are those who: have a communicable disease such as tuberculosis; have a dangerous physical or mental disorder, or are drug addicts; have committed certain criminal acts; are terrorists, subversives, members of a totalitarian party, or former Nazi war criminals; have used illegal means to enter the United States; or are ineligible for citizenship. Additionally certain former J-1 exchange visitors must live abroad two years before they can apply for an immigrant visa. Physicians who intend to practice medicine must pass a qualifying exam before receiving immigrant visas. If an individual is found to be ineligible for a visa, the law may provide for a waiver.