The three largest U.S. accounting firms ordered their partners not to poach clients or personnel from smaller rival KPMG LLP while it is under federal scrutiny for allegedly selling abusive tax shelters. The three firms are worried that KPMG\'s demise would leave thousands unemployed and possibly prompt authorities to order the breakup of the remaining firms. Without KPMG, ``life would be very awkward for the Big Three accounting firms,\'\' said Professor Stephen Calkins, an antitrust expert at the Wayne State University Law School . ``There would be more chance that government officials would decide that competition is not working here and something drastic needs to be done.\'\'