What plan was adopted to make sure china could remain autonomous and fair trade would exist between the nations?

This plan is known as the Open Door Policy.

This idea was introduced by Secretary of State John Hays in 1899. The goal of this plan was to ensure that all nations had the ability to trade with China. Even though this plan referred to the ability of all nations to trade with China, the real reason behind its development was the fear of the US government being blocked out of trading with China by European countries.

He advocated for a separation of powers of the government and the ones enforcing the law.