Convention on Road Traffic
(Geneva, 19 September 1949)
Article 9
1. All vehicular traffic proceeding in the same direction on any road shall keep to the same side of the road, which shall be uniform in each country for all roads. Domestic regulations concerning one-way traffic shall not be affected.
I suspect that hundreds of lives and millions of dollars are lost every year because the 1949 Convention on Road Traffic did not grasp the nettle and decide on one side or the other.
To make this decision today would be horrendously expensive but it should be done for the sake of future generations. Right or left could be determined at a new convention using a toss of a coin and those countries needing to change given a suitable time period (say until 1 Jan. 2020) to implement