Many firms are charging different hourly rates to different clients for similar work, according to a new analysis of more than $4bn (£2.8bn) in law firm billings, reports Corporate Counsel.

Differences in billing rates are just some of the preliminary findings in the new report by CT TyMetrix and The Corporate Executive Board, which examines billing from more than 4,000 law firms, 50,000 individual billers, and 18.9 million invoice items from 2007 to 2009.