The outcome of the Chicago Convention was the Convention on International Civil Aviation.
Article 5 (Non-Scheduled Flights Over States Territory) of the Chicago convention states that ‘the aircraft of states, other than scheduled international air services have the right to make flights across states territories and to make stops without obtaining prior permission…’
The Rules of the Air applicable to an aircraft registered in one state flying over another state shall be those of the state whose airspace is entered and transited.
The state in whose sovereign airspace the aircraft is operating is responsible for ensuring that an aircraft operating in a state's sovereign airspace complies with the rules and regulations which prevail in that airspace.
(Chicago Convention, 1944)