Mark Brandon, of Motive Legal who has been tracking the successful and not so successful hiring patterns within the legal sector for the past 5 years has produced a recent summary that might prove salutary reading. http://www.motivelegal.com/index.php/2012/09/has-the-lateral-partner-market-peaked/
Making sure your lateral hires stay with the firm - certainly at Partner level, requires not only a thorough selection process, including using psychometrics, but also integration coaching and performance mangement that will ensure you get the right person, delivering in the right manner. It doesnt have to end in tears.