Exceptions to restrictions on subsistence, lodging, or travel expenses under this chapter may be granted for the critically necessary work of an agency. For boards, commissions, councils, committees, or similar groups in agencies of the executive branch, the exceptions are subject to approval by the agency head or authorized designee. For boards, commissions, councils, committees, or similar groups in the executive branch under the purview of a separately elected official, president of an institution of higher education, chair, or executive director, the exceptions are subject to approval of the separately elected official, president of the institution of higher education, chair, or executive director. For agencies of the judicial branch, the exceptions shall be subject to approval of the chief justice of the supreme court. For the house of representatives and the senate, the exceptions shall be subject to the approval of the chief clerk of the house of representatives and the secretary of the senate, respectively, under the direction of the senate committee on facilities and operations and the executive rules committee of the house of representatives. For other legislative agencies, the exceptions shall be subject to approval of both the chief clerk of the house of representatives and the secretary of the senate under the direction of the senate committee on facilities and operations and the executive rules committee of the house of representatives.