The First Amendment can limit the expansion of trademark rights on the internet. This is the thesis of Margreth Barrett in her lengthy paper Domain Names, Trademarks, and the First Amendment: Searching for Meaningful Boundaries, Connecticut Law Review, vol. 39, 2007.
Quotation: "Unlike book, song and movie titles, the domain names may not identify or distinguish any goods or services for sale, so that First Amendment expression is not intertwined with commercial promotion, as in the case of books or movies. The domain names constitute pure expression."