That would be in matters of Federation law. Likely someone like Simon Tarses would be protected under Federation law since he's not on his home world.
Unless we believe every Federation citizen has the right to ceremonial combat to the death to possess a woman, each planet likely has its own laws that applies to its citizens. A Vulan woman may have certain rights as a Federation citizen when acting as a Federation citizen, but she would still be bound by the laws of Vulcan when living and working there. Even if it conflicts with Federation law.
Part of the issue is that the Federation went from a loose alliance of worlds in TOS to simply mimicking the US in TNG and other 24th century shows.