Legal Question in Family Law in California

She is, unfortunately, legally allowed to do that. Fortunately you have legal options of your own. If she has not been in WA with the child for more than six months, CA still has jurisdiction over the child. WA does not until your son has resided there with her for six months. It sounds like you are not married, so you don't file for a divorce, but you file pretty much the same paperwork to obtain custody and support orders when an unmarried couple with kids split up. That will include a request for an order that the child be returned to CA. Such orders are routinely granted in these kinds of cases unless there is substantial evidence that it would be bad for the child, and even then the parent who has gone out of state will often be required to post a bond to assure that the child will be returned to CA if that is the final outcome of the custody case. Because of the cross-jurisdiction complexities, I cannot urge you strongly enough to use a lawyer. Most family law lawyers have ways to make their services affordable by most people.