Legal and Political Implications of Multidirectional Links

When Out-of-line is 'out of line'

Linking to content you don't control Multidirectional links could conceivably originate from content outside of your site. Other users can provide annotations on their own pages, which users traveling from those pages to your pages will see.
Already enough lawyers Even 'traditional' HTML linking has been enough to generate lawsuits. Being able to link documents externally and reference fragments (through XPointer) is going to bring out a whole new set of issues.
Potentially offensive content What's annotation and what's graffiti? You decide.