Earlier quoted context omitted.
In fact, as far as I know the only European states that are not part of ECHR and Council of Europe are the Vatican (since they're a theocracy...), Kosovo since it has limited international recognition, Kazakhstan and Belarus over human rights violations. No European state that'd be eligible has chosen to voluntarily stay outside. Azerbaijan and Russia are the closest to being in trouble of the current members (Russia…
It's surprising to find that the ECHR does not consider same-sex marriage a human right.
>> Article 14 – Prohibition of discrimination:
>> The enjoyment of the rights and freedoms set forth in this Convention shall be secured without discrimination on any ground such as sex, race, colour, language, religion, political or other opinion, national or social origin, association with a national minority, property, birth or other status. [0]
Granted, its not about marriage, but according to the ECHR, its a human right to live free of discrimination based on sexual orientation.
[0]: https://www.coe.int/en/web/conventions/full-list/-/conventio...