HP, Sun and Accenture are co-operating with investigators looking into whistleblower lawsuits filed by the US Department of Justice and alleging the three companies paid and received kickbacks in exchange for preferential treatment in government contracts. 

The lawauits, originally filed by whistleblowers, was joined yesterday by the Department of Justice and allege the companies submitted false claims to the US government on a number of contracts in the last decade.
The lawsuits go on to allege the accused companies of creating alliance relationships with other vendors, giving each other discounts or rebates on government work, which were not passed on to their clients. According to US law, rebates have to be passed back to the government.