Section 17. The superior court shall be open at all times, except on nonjudicial days, for the determination of non-jury civil cases and the transaction of business. For the determination of civil causes and matters in which a jury demand has been entered, and for the trial of criminal causes, a trial jury shall be drawn and summoned from the body of the county, as provided by law. The right of jury trial as provided by this constitution shall remain inviolate, but trial by jury may be waived by the parties in any civil cause or by the parties with the consent of the court in any criminal cause. Grand juries shall be drawn and summoned only by order of the superior court.