If a nonimmigrant alien (for example, a tourist) enters the United States illegally or enters legally but violates his or her nonimmigrant status, the alien is considered to be an undocumented alien. If an alien accepts unauthorized employment, remains longer than permitted, or commits one of several other violations, the alien has violated his or her nonimmigrant status. Some of these undocumented aliens purchase counterfeit documents or assume another person's identity by using fraudulently obtained genuine documents. R.G. is a nonimmigrant alien who is living in the United States.