When Alice came visit Bella in NewMoon,Jake said he couldn't protect her because he was in"their land"he didn't want to break the treaty.when they left for volterra he said"i'll protect charlie screw the treaty"Why would any of that breakthe treaty?
Jacob technically broke the treaty in Twilight, by telling Bella the story. Since both frequent the Swan house, it may be neutral ground, because of Bella.
Forks is a common land,it`s the Switzerland.Both Edward(vampires) and Jacob(werewolfs) can be here.I think Jake said that,like "Now YOUR vampires come,so I can be near you,near them..."
something like that,,,
