22 GCA § 3223: Changes in Employment Contracts: Discrimination.

If an employment contract for a non-immigrant alien worker to work in Guam has been previously submitted to the Guam Department of Labor, the U.S. Department of Labor, the U.S. Immigration and Naturalization Service, or the U.S. State Department as part of a process to obtain a visa or permission to work in the United States, then any prior or subsequent replacement, modification or amendment thereto is enforceable by the employer and may benefit the employer only if it is legal and not contrary to public policy and only if it is submitted to the Department of labor, and is approved in writing by the Department of Labor. Such submission and approval are not required if the only modification is to increase the wages of the employee. It shall be a felony of the second degree for an employer to knowingly employ, compensate, or provide preference to non-immigrant workers over local workers, or to discriminate against local workers in the employment or compensation of non-immigrant workers