Originally Posted by aka123

This is more complicated than that because this goes beyond domains aka extending to trademarks. It can for example be possible that trademark owner cannot stop you aquiring or keeping some domain, but can prevent using it.

And the dot com owner can always make claim against your trademark, succeeding is a different matter as in any battle.

The best layer of protection can be aquired by registering critical domains, extensions and misspellings, trademarks and registering domain as your company name alias (you can have as many aliases as you want).