In order to prove a claim for defamation in California, a person must prove the following elements by a preponderance of the evidence, that is, it is more likely than not that each element is satisfied based on the evidence.
1) Defamatory - the statement must be defamatory. What does that mean? It has been defined as any statement that tends to lower the reputation of a person in the community, and/or subject that person to contempt, ridicule, or obloquy, or cause the person to be shunned or avoided. For example, what if a newspaper described a person as being "gay?" Would that be defamatory? Well, it depends on the community. Obviously, in most places in California and, indeed in the United States, such a statement would clearly not be defamatory. But what if that statement was written in a small town newspaper in the south, for example? In that situation, the statement may be found to be defamatory.
2) Statement of Fact - the statement must be a fact. Generally, you would not be able to prove defamation if the statement is an epithet, hyperbole, or is merely an opinion. That is not to say that all opinions are created equal. Some statements that appear to be opinions may be construed to be factual statements if the statement implies a provably false statement. This is one of the most misunderstood concepts relating to defamation law. I talk more about this here.
3) Falsity - the statement or statements must be false.
4) Of and Concerning - The average reasonable person must understand that the statement refers to the plaintiff, and not someone else, or a group of other people.
5) Publication - this element is a bit misleading. A statement can be published in a number of ways, including orally, in writing, by photograph, or other fixed means, and, it must be conveyed to a third party. So, if Mr. Jones comes up to you and claims that you've been convicted of a crime, it's not going to count as defamation unless a third party heard the statement.
6) Causing - The statement must cause the plaintiff harm to his or her reputation.
7) Damages - Damages are presumed and therefore do not need to be proved if the statement is slanderous on its face or if it is libelous. A statement is slanderous on its face if it falls into on one of the four categories listed on pages 5-6. A statement is libelous if it is in permanent form. For instance, any statement on the Internet would be libelous; any photograph that is defamatory would be libelous as well since it is fixed.
Each of the above elements must be proved by a preponderance of the evidence in order prevail on a claim of defamation.