Thanks for the deets. Do you know if UK has courts that handle people who sue one another? It looks as if you can file suit against the UK government. I'm genuinely curious, has someone with evidence of ownership sued the British Museum?
I can see a compelling argument someone might claim ownership of the stone, I'm curious where in the process they were shut down, if they didn't try, or they did and their suit was dismissed.
Hague Convention of 1907
1970 UNESCO
1995 UNIDROIT
US:
https://en.m.wikipedia.org/wiki/Lieber_Code
2004 HR1047 section 204.
(Those are more about stopping theft / destruction- not return.)
UK:
Except for human tissue, it’s basically not legally regulated.
Australia:
No laws. There is a government program for aboriginal art and remains.
But as an example, Egypt frequently requests the return of the Rosetta Stone from the British Museum.