OK. You perked up my interest to actually look up the 1930 treaty:
Text:
http://eudo-citizenship.eu/Internati...ULL%20TEXT.pdf
Ratifiers:
https://treaties.un.org/Pages/LONVie...r=30&clang=_en
You're right, probably not enforced outside the 20
(Did Canada denounce the 1930 treaty on 15 May 1996?!)
We shouldn't look at the 1930 treaty as the source of the Master Nationality Rule
We're down to local laws [see footnote].
Well not explicitly.
But by accepting the other state's passport for entry, the accepting state may be implicitly accepting the other state's request to afford the bearer "every assistance and protection" (Australian)/"such assistance and protection" (UK) as stated in the passport note? This may put the accepting state in a moral quandary even if not a strict legal one.
Furthermore it may put the accepting state in breach of consular treaties, unless it has explicit renunciation of dual nationality e.g.
https://treaties.un.org/doc/Publicat...19-English.pdf
(I misread) exit no.
jazzsax probably did nothing wrong in law.
I wonder will CBSA have some red flags against his Jamaican passport for entry (how come this passport has exit records but no entry?)
But I suspect CBSA will never be presented the passport for entry, as jazzsax will present his Canadian passport for entry all the time.
===
[Footnote - side track]
i) USA enforces Master Nationality Rule even though it is not a 1930 treaty signatory
ii) I'm more familiar with the Australian and HK case as both enforce the rule and are 1930 signatories
iii) PRC is not a 1930 treaty signatory but enforce Master Nationality Rule in a
big way - to the extent they demanded Canadians they suspect to be Chinese citizens to obtain China Travel Documents to proceed to China
iv) ROC is the 1930 China signatory but they disclaimed Article 4.
And I think they mean it - I am treated as an Australian in Taiwan, even though I can also be treated as a ROC Citizen outside Mainland Area.