U.S. law regarding employment-based migration is primarily governed by the Immigration and Nationality Act (INA). This legislation outlines various visa categories that allow foreign nationals to enter and work in the United States. The employment-based immigration system is divided into several preference categories, including:

1. EB-1 (Employment-Based First Preference): Priority Workers, including individuals with extraordinary ability, outstanding professors and researchers, and multinational executives and managers.
2. EB-2 (Employment-Based Second Preference): Professionals with advanced degrees or exceptional ability.
3. EB-3 (Employment-Based Third Preference): Skilled workers, professionals, and other workers.
4. EB-4 (Employment-Based Fourth Preference): Special immigrants, including religious workers, certain broadcasters, and employees of U.S. foreign service posts.
5. EB-5 (Employment-Based Fifth Preference): Immigrant investors who contribute to job creation and economic development.

The process typically involves a sponsoring employer filing a petition on behalf of the foreign worker. The availability of visas is often subject to numerical limitations, and applicants may need to go through a labor certification process in certain cases.

It’s important to note that immigration laws are subject to change, and individuals seeking employment-based migration should consult with legal professionals or the U.S. Citizenship and Immigration Services (USCIS) for the most up-to-date information.