• The USCIS provides procedures and enforces laws for immigration.plane image by Vlaad T from Fotolia.com
  
  The United States Citizenship and Immigration Services (USCIS) is a department of the United States Department of Homeland Security. The agency is responsible for issuing employment authorization documents, granting permanent resident status, granting U.S. citizenship, and implementing and enforcing immigration policies. State governments also have their own immigration policies, but must obey all national immigration laws. In addition, if any state laws come in conflict with national laws, the national law always has priority.
  
  

Issuing Visas

• The Immigration and Nationality Act mainly addresses the processes of immigrating to the U.S. and attaining U.S. citizenship. Under the act, the specifications for issuing visas is listed. Visas can only be issued to immigrants who have filled out a visa application as listed in section 222 of the Immigration and Nationality Act and approved by an officer. Immigrants must also list the country from which they originate and their citizenship status in that foreign country. Immigration visas cannot exceed six months, except visas issued to children who have been legally adopted by United States citizens. This condition also does not apply to immigrants who are employed by the United States government. The secretary of state can prescribe additional visa validity time if the immigrant has been granted special treatment by foreign governments, such as refugees.
  
  

Documentary Requirements for Immigrants

• Immigrants can only be admitted into the United States if they have a valid unexpired immigrant visa or were born at the time their parents were issued a visa. Immigrants must also have a valid passport or document of identity or nationality.
  
  

Health and Behavioral Requirements for Immigrants

• All immigrants in the United States must have received vaccines against vaccine-preventable diseases, such as mumps, measles, rubella, tetanus, pertussis, influenza type B, hepatitis type B and any other vaccinations recommended by the Advisory Committee for Immunization Practices, which provides advice on vaccine-preventable diseases to the U.S. population. Immigrants must be free of physical or mental disorder and dangerous behaviors that might pose or have posed a threat to other individual's safety, property, or welfare. Immigrants who are determined to be drug abusers or addicts under regulations presented by the Secretary of Health and Human Services are not to be admitted into the United States.