There is an art to checking references. Even if a company has a policy of giving bare minimum information, find out a TELEPHONE NUMBER of someone in that company who knows your candidate and start a conversation. I was given a specific script of questions to ask back in the 1990s when I was a community volunteer for my local public school district, doing reference checks on superintendent candidates. A consultant advised the school district (and through the district, me) on how to do this. If you talk to someone directly by voice, and have a good list of specific questions to ask about the candidate, you will be AMAZED at what people say, policy or no policy. Company policies don't keep people from sharing stories with curious listeners. The key is to learn what questions are legal to ask and reveal the most interesting stories about the person you are thinking of hiring. There are consultants who can advise you about checking references, and, as several comments here say, they are a lot less expensive than making a wrong hiring decision, and once you've learned the questions, you know what to ask.

I've just asked my consultant Google, and he suggests several sets of useful questions to ask when checking references:

http://hiring.monster.com/hr/hr-best-practices/recruiting-hi...

http://www.drgnyc.com/list_serve/Jan24_2005.htm

http://www.acadweb.wwu.edu/hr/Employment/InfoForHiringOffici...

http://www.best-job-interview.com/reference-check-questions....

http://www.k-state.edu/hr/employment/referencecheck.htm

http://pbsbo.ucsc.edu/personnel_payroll/staff/recruit/ref_ch...

http://www.bridgestar.org/Library/HiringToolkit/ReferenceChe...

http://jobsearch.about.com/od/referencesrecommendations/a/re...