All goods imported into the United States must be made in factories that adhere to all US labor and environmental laws and regulations, at a minimum.
Leveling the playing field gives multi-national corporations less of a reason to manufacture overseas.
1) They will pay the same minimum wage as they do in the U.S.
2) They will follow the same Fair Labor Standards Act requirements.
3) They will follow the same OSHA regulations.
4) They will have the same environmental requirements.
Other benefits include less worldwide pollution and a safer environment for overseas factory workers.