At one large bank, all attorneys may approve the invoices that are their responsibility regardless of the amount of the invoice. Other law departments grant authority in step with the level of its lawyers (See my post of Sept. 17, 2005 #3 where over $100,000 requires AGC signoff; Aug. 24, 2005 and $10,000 limits for most lawyers; and April 26, 2006 about our fixation on approval levels by title.).
Accompanying the attorney review and approval for the bank mentioned is scrutiny – one hopes – by someone in finance and by a client representative whose unit will be charged for the bill. It makes sense to raise the lawyer authority level when there are two other employees who must also look at and signoff on bills.