Excerpt: It is appropriate for Spitzer to investigate bid rigging, says J. David Cummins, a professor of insurance and risk management at Wharton. But he draws the line at eliminating contingent commissions. 'Contingent commissions can help keep property-casualty and other markets efficient,' says Cummins, the executive director of Wharton's S.S. Huebner Foundation. 'The practice may actually level the playing field by giving buyers and sellers equal access to vital market information.'