Before entering the United States, a non-U.S. traveler must have a visa. Whether the traveler is seeking to immigrate to the U.S. or simply intends to visit the country on a tourist visa, they must go through the visa application process.
The first step in the process is to apply for visa through a U.S. Consulate in the applicant's own country. Upon arrival in Miami or any other port of entry, U.S. Citizenship and Immigration Services will screen the applicant to make sure they are eligible to enter the country.
A U.S. visa can be denied for a number of reasons. A person who has been convicted of a crime involving moral turpitude will be ineligible. Similarly, drug traffickers or family members who benefited from the drug trafficking will be unable to get a U.S. visa. Anyone involved in human trafficking or money laundering will also be ineligible.
A visa application can also be denied for health reasons. Someone with a communicable disease that presents a risk to public health can be denied a visa. Being HIV or AIDS positive does not, however, fall into this category. A drug addict or drug abuser is also ineligible. Finally, an applicant must be able to show proof that they have been vaccinated against measles, mumps, influenza type B, hepatitis B and other diseases.
A U.S. visa can also be denied if the applicant is deemed to be a security threat; is likely to become dependent on government assistance in the U.S.; or has previously violated U.S. immigration laws.
If a visa applicant is deemed to be ineligible, it is sometimes possible to obtain a waiver of ineligibility that will allow the person to enter the country. This can be a complex process and requires a skillful presentation of the facts and an understanding of U.S. immigration law. A knowledgeable immigration attorney can be of invaluable assistance to a person in this situation.
Source: Findlaw.com, "Visas: Reasons for Ineligibility," accessed on May 29, 2016