Wash. Rev. Code § 2.08.010
The superior court shall have original jurisdiction in all cases in equity, and in all cases at law which involve the title or possession of real property, or the legality of any tax, impost, assessment, toll or municipal fine, and in all other cases in which the demand or the value of the property in controversy amounts to three hundred dollars, and in all criminal cases amounting to felony, and in all cases of misdemeanor not otherwise provided for by law; of actions of forcible entry and detainer; of proceedings in insolvency; of actions to prevent or abate a nuisance; of all matters of probate, of divorce and for annulment of marriage, and for such special cases and proceedings as are not otherwise provided for; and shall also have original jurisdiction in all cases and of all proceedings in which jurisdiction shall not have been by law vested exclusively in some other court, and shall have the power of naturalization and to issue papers therefor. Said courts and their judges shall have power to issue writs of mandamus, quo warranto, review, certiorari, prohibition and writs of habeas corpus on petition by or on behalf of any person in actual custody in their respective counties. Injunctions and writs of prohibition and of habeas corpus may be issued on legal holidays and nonjudicial days.
RCW 2.08.010
Jurisdiction of superior courts: State Constitution Art. 4 s 6 (Amendment 28).