Defamation is a blanket term for a statement that injures someone’s reputation. Written defamation is called “libel.” Spoken defamation is called “slander.” In almost all states, defamation is not a crime. However, a defamed person can sue the defamer. The public perception of what constitutes “defamation” is quite different from the legal definition. This causes disappointment for many would-be litigants. In a defamation lawsuit, the defamed person must prove that there’s been a statement that is all of the following: 1) published, 2) false, 3) injurious, and 4) unprivileged.
Importantly, the statement must be false. Even if the statement is incredibly mean or nasty, if it looks like an opinion, it is not defamation. The plaintiff must prove that it is objectively false. Truth is always a defense in a defamation lawsuit.
A great deal of defamation happens online, especially with anonymous lies about a person’s sexual health, infidelity, criminal record. Online service providers generally can’t be held liable for content that user’s post. They can, however, be asked to remove defamatory content and can be subpoenaed to provide user information (e.g. IP address, etc) about the person who posted the information.
Remember: if it’s true, it’s not defamation, though it may trigger different invasion of privacy claims, depending on the state where the case will be brought. An attorney can figure out the best way of addressing your situation to get you the best possible outcome.