You can write whatever you want in your blog. No one is going to stop you. However, that doesn't mean there aren't consequences for your actions. Defamation

You can write whatever you want in your blog. No one is going to stop you. However, that doesn't mean there aren't consequences for your actions. Defamation can occur, and can be pursed legally against you, if you publish a blog where you knowingly proclaim something false that damages someone's reputation.