An employer must follow the strictest child labor laws, state or federal. To determine which law the employer of employees over the age of 17 is covered by, an employer that grosses over $500,000.00 per year or is engaged in interstate commerce is subject to the federal law. An employer that grosses less than $500,000.00 per year and is not engaged in interstate commerce but has four or more employees is subject to the state wage and hour laws.