SAN FRANCISCO — Defense lawyers for former Autonomy CFO Sushovan Hussain have lost out in their attempt to force federal prosecutors to scour the files of a private law firm involved in a related corporate investigation. 

Lawyers at Keker, Van Nest & Peters had asked U.S. District Judge Charles Breyer to rule that the government’s obligation to disclose favorable evidence extended to the Morgan, Lewis & Bockius investigation of Hewlett-Packard Co.’s botched deal with Autonomy. The Silicon Valley company and its lawyers acted as an “unofficial member” of the prosecution team that built a case against Hussain for alleged wire fraud, the defense team asserted.