One way to combat the cost creep that comes from converging to large law firms is to look for smaller firms that join together to propose on work. So long as one of the firms assumes the lead role, the law department can get the best of all worlds: lower cost structure and better quality with the same administrative burden.
To permit joint bids may mean that the law department has to give proposers more time to negotiate such arrangements. It may make evaluation of proposals more complicated. It may create a different kind of uncertainty about coordination and performance — but the dollars saved can be piled high.