Immigration law in United States

Immigration law in the United States is mainly federal law. Congress creates the basic rules, and federal agencies handle applications, border inspection, visas, work permission, naturalization, detention, and removal proceedings. Common legal categories include nonimmigrant visas for temporary visits or activities, immigrant visas for permanent residence, lawful permanent resident status, refugee or asylum protection, and citizenship through naturalization or another legal route. Each category has different rights and limits. A person may enter through a visa, a family petition, employment sponsorship, humanitarian program, admission at the border, or another process. A visa is generally permission to seek entry, while the period and conditions of authorized stay are determined through the immigration process and admission record. Lawful permanent residents, often called green card holders, may live and work in the United States but can still face immigration consequences for certain conduct or prolonged absence. They also must meet legal requirements before applying for naturalization. The system uses applications, petitions, interviews, background checks, supporting documents, medical or identity records in some processes, and decisions by agencies or immigration courts. A denial, notice, request for evidence, or court hearing may require a different response. Asylum and refugee protection are related humanitarian systems but are not identical. In general, asylum is sought by a person who is in or has reached the United States, while refugee processing is generally connected with protection sought from outside the country. Immigration consequences can depend on prior entries, overstays, unauthorized work, arrests, convictions, false statements, family relationships, and travel history. A criminal case or missed immigration notice can affect options even when the person has lived in the United States for many years. The main limits are that immigration rules are technical, facts must be truthful and consistent, and a missed notice can cause serious harm. People should keep copies of every filing and notice and seek qualified immigration help when the case involves removal, detention, fraud concerns, criminal history, or a complicated past.