Being inadmissible is a state in which an individual is not allowed to legally enter the United States, or to obtain immigration documentation such as Visas. This is usually based on the individual’s conduct. The acts that could lead to inadmissibility are listed in section 212 of the Immigration and Nationality Act, and seek to protect the country from elements that might pose a risk to the American public. When inadmissible, an individual who otherwise gains access to the country runs the risk of litigation, and can have legal penalties instituted upon them. They can also be deported back to their home country.

One of the grounds for inadmissibility is health-related. Foreign nationals can only get visas and allowance into the country if they prove that they are free of communicable diseases of public significance including chancroid, gonorrhea, granuloma inguinale, infectious leprosy, infectious syphilis and active tuberculosis. Any quarantinable disease also falls into this category. Foreigners who suffer from mental or physical disorders or drug addiction may also be inadmissible. Proof of vaccination against various diseases including yellow fever from foreigners from tropical countries is necessary to ensure that they are admissible.

Inadmissibility can also be based on criminal grounds. Foreign nationals who have a history of conviction or who commit acts which could be considered crimes involving moral turpitude are automatically inadmissible to the state. These include arson, murder, rape, robbery and larceny. Offenses relating to controlled substances, such as previous incarceration for dealing with hard drugs such as cocaine, are also grounds for inadmissibility. Some grounds of inadmissibility in this class can be argued out.

Other elements that can make one inadmissible include involvement in economic fraud, lack of the requisite documentation, previous deportation or removal from the United States and practicing polygamists.