The Chicago Convention is an international treaty that, along with the Warsaw Convention and the Montreal Convention, governs international aviation. Most of the safety rules followed by international airlines today began with the Chicago Convention.
In 1944, it become apparent that the advancements in the field of aviation spurred on by World War II would require a new set of laws to address the rising use of air commerce and travel once the war was over. The U.S. government invited representatives from over fifty allied nations to the Convention on International Civil Aviation (later known as the Chicago Convention) to develop these laws. Germany and Japan were not involved. The Soviet Union was invited but did not show up.
The Chicago Convention laid the foundation for all international rules regarding safety, airspace, aircraft registration, pilot licensing and even crash investigations. It also established the International Civil Aviation Organization (ICAO) in Montreal to act as a governing body to codify, maintain and continue to develop wide-ranging standards and regulations followed by most of the nations and carriers operating in the world today.
Photo source family archives of Dominique Hymans, son of Max Hymans via Wikipedia.