Look, no matter who's collar one wears, they need but take it off and leave if they no longer wish to be in it. Thats the Consensual part of SSC. Just becuase one submitts to another, doesn't mean they stop being human or stop having legal rights under the laws of one's country.

Of course its polite to ask (which in and of itself shouldnt be an issue, simpley courteous thing to do).

And if the so called dominant has a problem with it and trys to restrain one against one's will or starts stalking one, well then its time to get the cops involved.

As for being "collared" and wearing a collar, those are two different animals. My Owner doesn't have me wear a collar in public unless its in certian venues where it is socially acceptable. Many submissives and even slaves do not wear anything at all that would reveal the nature of their relationship to the uninitiated.