Whenever in any proceedings, civil or criminal, legal or equitable, in the superior court or in any district court, any question of law shall arise or the constitutionality of an act of the general assembly shall be brought in question upon the record, which, in the opinion of the court, or in the opinion of the attorney general if the state is a party to the proceeding or if he or she has intervened therein, is of such doubt and importance and so affects the merits of the controversy that it ought to be determined by the supreme court before further proceedings, the court in which the cause is pending shall certify the question or motion to the supreme court for that purpose and stay all further proceedings until the question is heard and determined; provided, that no question shall be so certified in any criminal case where the defendant has not been released on bail.