Background Check Catch 22

When you do even a simple background check like we do (ss# and criminal check in 1 or 2 counties) you need a social security # and a date of birth. Aren't these things you can't ask for? How do you approach this - do you tell someone that they are hired pending the outcome of the background check? What if you want to decide between 2 or 3 people and use this as one method to eliminate someone? How do you stay legal and still get the information you want?
Comments
Thanks so much!
Ann