If a lawsuit is filed in state court, the defendant may remove the lawsuit to federal court if there is a basis for the federal court to have jurisdiction over the lawsuit—either because the plaintiff has alleged a violation of federal law (the U.S. Constitution, a federal statute, or a treaty to which the United States is a party), or because there is complete diversity of citizenship between the parties—meaning no plaintiff is a citizen of the same state as any defendant—whether the parties are persons or entities.

If the defendant files the documents necessary to remove a lawsuit filed in state court to federal court, the plaintiff then generally has 30 days to request the federal court remand (send) the lawsuit back to the state court on the basis that the federal court does not have jurisdiction over the matter.

In Washington state, as in other states, a defendant has the right to remove a lawsuit from state court to federal court if certain conditions are met. This can occur if the lawsuit involves a federal question, meaning that the plaintiff's claim is based on federal law, or if there is diversity of citizenship, where no plaintiff shares the same state citizenship with any defendant. Entities, as well as individuals, are considered for determining citizenship. Once the defendant has successfully filed for removal, the plaintiff may challenge the removal by filing a motion to remand the case back to state court within 30 days. The plaintiff must argue that the federal court lacks jurisdiction, either because the case does not actually involve a federal question or because the parties are not diverse. The federal court will then decide whether to keep the case or remand it back to state court.