What is immigration?

On March 1 2003, the Immigration Department (INS) of the US Department of Justice, which had been established for 69 years, was merged into the Ministry of National Security, and was divided into three agencies: Citizenship and Immigration Service (BCIS), Customs and Border Protection (BCBP) and Immigration and Customs Enforcement (BICE).

The US Immigration Service is attached to the US Department of Justice. The enforcement power of immigration law belongs to the Minister of Justice, but the Minister of Justice usually authorizes the Immigration Bureau, so the Immigration Bureau has become the core enforcement agency of immigration law, responsible for handling immigration and non-immigration applications, foreigners' entry and exit, border patrol, arrest and expulsion of illegal foreigners, refugee review, and punishment of illegal employment. Ordinary foreigners have the most contact with four regional immigration service centers that directly accept immigrant and non-immigrant applications, as well as regional offices and sub-offices that handle daily immigration affairs. The latter is commonly known as "local bureau".