Foreign nationals may be inadmissible due to the commission of a crime involving moral turpitude (CIMT). CIMT includes fraud, arson, blackmail, burglary, theft and others.
Any alien convicted of, or who admits having committed, or who admits committing acts which constitute the essential elements of a crime involving moral turpitude (other than a purely political offense) or an attempt or conspiracy to commit such a crime is inadmissible.
However it shall not apply to an alien who committed only one crime if the crime was committed when the alien was under 18 years of age, and the crime was committed (and the alien released from any confinement to a prison or correctional institution imposed for the crime) more than 5 years before the date of application for a visa or other documentation and the date of application for admission to the United States, or
the maximum penalty possible for the crime of which the alien was convicted (or which the alien admits having committed or of which the acts that the alien admits having committed constituted the essential elements) did not exceed imprisonment for one year and, if the alien was convicted of such crime, the alien was not sentenced to a term of imprisonment in excess of 6 months (regardless of the extent to which the sentence was ultimately executed).