The EFF have published a Legal Guide for Bloggers to help bloggers deal with the legal issues surrounding blogging:

To be clear, this guide isn't a substitute for, nor does it constitute, legal advice. Only an attorney who knows the details of your particular situation can provide the kind of advice you need if you're being threatened with a lawsuit. The goal here is to give you a basic roadmap to the legal issues you may confront as a blogger, to let you know you have rights, and to encourage you to blog freely with the knowledge that your legitimate speech is protected.

And it only applies to blogging in the US.