Code of Civil Procedure section 259, subdivision (a) authorizes a court commissioner to determine ex parte writ petitions; the statute is constitutional. Two inmates filed petitions for writ of mandate seeking an order directing the prison to process administrative appeals of grievances. A court commissioner denied the petitions. In the Court of Appeal, the inmates challenged the commissioner’s jurisdiction and the court concluded that the commissioner had authority to deny the petitions. The California Supreme Court affirmed. The plain language of Code of Civil Procedure section 259, subdivision (a) authorizes court commissioners to grant or deny ex parte petitions for writs of habeas corpus and alternative writs. The reference in subdivision (a) to a “motion” is a broad term that includes petitions for alterative writs or writs of habeas corpus because a writ petition may fairly be described as an application for an order, which is the definition of a “motion.” The authority to “hear and determine” a matter is a grant of subject matter jurisdiction and includes the authority to deny a requested writ. The constitutional authority of commissioners to perform “subordinate judicial duties” includes the decision to summarily deny an ex parte petition for writ of mandate or habeas corpus. The limitations applied to writ proceedings (i.e., In re Clark (1993) 5 Cal.4th 750, 767; federal exhaustion and procedural default rules) do not negate a commissioner’s authority under the present circumstances. This is not akin to a judicial proceeding because no hearing or other input from the respondent is required. It was unnecessary for the court to decide whether assigning a commissioner to a case that challenged a criminal conviction or asserted grounds for release from confinement would be constitutional.