There are no legal battle if it's two individuals, First come first serve, even if you're not "John Smith", a john smith got no rights in taking that off you, unless of course you use that name "person against" for profit reason.
e.g.

the site is talking about the person in question.

you approached the person to sell your domain.

And one, which i see it happening. you have no use of the domain name, a aign you're waiting for a buyer. - like parking and undeveloped sites