The Advocate General, the Lord Advocate or the Attorney General may refer the question of whether a Bill or any provision of a Bill would be within the legislative competence of the Parliament to the Supreme Court for decision.
Subject to subsection (3), he may make a reference in relation to a Bill at any time during—
the period of four weeks beginning with the passing of the Bill, and
any period of four weeks beginning with any ... approval of the Bill in accordance with standing orders made by virtue of section 36(5).
He shall not make a reference in relation to a Bill if he has notified the Presiding Officer that he does not intend to make a reference in relation to the Bill, unless the Bill has been approved as mentioned in subsection (2)(b) since the notification.