Here’s the section of the Idaho Constitution – Article IV, Section 9 – that empowers the governor to call special sessions of the Legislature, and limit what can be considered at the special session:

ARTICLE IV EXECUTIVE DEPARTMENT

Section 9.  EXTRA SESSIONS OF LEGISLATURE. The governor may, on extraordinary occasions, convene the legislature by proclamation, stating the purposes for which he has convened it; but when so convened it shall have no power to legislate on any subjects other than those specified in the proclamation; but may provide for the expenses of the session and other matters incidental thereto. He may also, by proclamation, convene the senate in extraordinary session for the transaction of executive business.

Gov. Butch Otter's press conference is set for 10:30 MT this morning; you can watch live here. Idaho Statesman reporter Bill Dentzer has an analysis here from today's paper, concluding that a "perfect legislative storm" led to the state's quandary over its child support enforcement system, and the need for the first special legislative session since 2006. While the child support enforcement bill was being killed in a House committee in the session's final days, Dentzer writes, most lawmakers were paying more attention to the "going home bill," a transportation funding compromise being hashed out in a House-Senate conference committee. The child support enforcement bill became the "coming back bill."