Group Leader Authorization can be granted by the department head responsible for the validation of the business purpose and need for the group travel. Authorization should be granted before the trip. The only documentation needed as evidence of this authorization is the grantor's approval of the expense report; that approval can stay on file in the department.
Note: Group Leader Authorization is not granted simply for the convenience of submitting one travel voucher for multiple travelers. There must be a valid reason why one person must pay the expenses of a group.