The decision of a New Jersey court to order a blogger to reveal her sources is another stark reminder that the worlds of user-generated content and social media are just as subject to defamation procedures as professionally produced content.

Life coach Shellee Hale made comments on various online forums about a software company called Too Much Media, which subsequently sued her for defamation. The court ruled Hale was not a “professional journalist” and was therefore not subject to the right to ...