According to the Online Journalism Association, writing a blog is not considered an act of journalism. This means that you cannot be sued for defamation if you write something false or inaccurate about someone on your blog. However, if you write something that is defamatory but not factually inaccurate, you may be liable for libel. Libel is a criminal libel law that makes it illegal to publish false and defamatory statements about another person with the intent to harm their reputation.
If you are found guilty of libel, you could face jail time and a hefty fine. Therefore, it is important to be careful when writing about other people on your blog, as there is potential for retribution if things go wrong.