Is it a statement of fact published to a third party?
The statement in question has to be one of fact, thus a stated opinion cannot be defamatory. However, an opinion statement that strongly implies the maker is aware of undisclosed facts may be actionable. The statement must also be published to a third party, meaning that it must be directed (in writing or orally) to individuals other than the maker or the maker's agents and you. For example, if the statement occurred in the privacy of your own home with only you and the maker present, defamation does not exist.
Is the statement false?
Defamation (traditionally known as libel and slander) can only occur when the statement in question is factually false. If the statement is based in truth, it is not defamatory. There may be a mixture of truth and falsity in the statement, but you can only recover for the damages you suffered which you can prove were directly caused by the false portions of that statement. The maker of the statement will always have a solid defense if the maker can prove that what was said is true.
Is the statement defamatory?
In addition to being false, the statement must subject you to hatred, contempt or ridicule. Thus, the statement must be about you personally and individually, and the third party to whom it is published must understand and be able to identify you as the target of the statement. You can show that the statement is defamatory if you can prove that it lowered you in the estimation of the community or cost you personal or business opportunities with other people.
Have you suffered damages?
The general rule in Washington is that you must be able to prove that as a direct cause of the false and defamatory statement you suffered actual damages. You must be able to point to specific things you have lost or been deprived of as a result of the statement. Merely feeling angry, sad or embarrassed as a result of the statement is usually not enough to constitute recoverable damages.
Is the statement privileged?
Certain types of statements are said to be privileged, meaning that though the statement may prove injurious to you, you still cannot recover damages for defamation. Statements made in legislative or other government proceedings are almost always privileged. There is limited protection for someone who republishes the original statement, so long as the republisher clearly cites the original maker of the statement. Another privilege exists where a common interest is furthered by the communication between the maker of the statement and the third party to whom it is published, particularly where the maker can show that the third party was entitled to the information. The concept of privilege can become complex and difficult, and you should consult with an attorney to determine if the statement might have been privileged.
Seek legal advice
There is more to the law of defamation than outlined above, and ultimately the legal rules surrounding a defamatory statement can be very complex. If after reviewing the above you believe you are the victim of defamation, you should consult an attorney who can aid you in determining whether your claim is actionable.