The first thing you need to know about is the Fair Credit Reporting Act. I'm not certain if FCRA comes into play if the source of your report comes from the Sheriff. On the other hand, if your report comes from the Sheriff, you will probably not be able to get a report that encompasses other states or that will be based on an actual paper document check and computer records are often well behind.
Hitting a local employment law update through SHRM wouldn't be a bad idea, either, as there are several kinds of checks you can do and you don't want to do any that are not "job related" and you don't want to spend money needlessly.