Do ICAO specifications have the force of regulation? ICAO, the International Civil Aviation Organization, has specifications for the conduct of civil aviation throughout the world. Such things as the language to be used between controllers and pilots, aircraft calls signs, and a host of other things are covered. At the time of my retirement in 1999, the ICAO specifications were merely recommendations, they did not have the force of regulation in the U.S. or, to the best of my knowledge, in any country in which I operated. Is that still true? Is there any country that says, essentially, that if ICAO says it should be so, the country treats that as a regulation.
According to About ICAO from their own site:


  ICAO works with the Convention’s 191 Signatory States and global industry and aviation organizations to develop international Standards and Recommended Practices (SARPs) which are then used by States when they develop their legally-binding national civil aviation regulations. 


So ICAO continues to develop standards and recommendations without the force of regulation.