Government contractor's must abide by drug-free workplace. A candidate divulges details of a DUI and is not in a protected class,
Trying to think of any possible ramification if we do not offer the candidate the position.
The person is a member of a protected class. For example, he or she has a race. By law, you may not consider his or her race as part of an employment decision. That shouldn't even be part of the discussion.
A DUI is not evidence of either alcoholism or use of illegal drugs. I do not condone drunk driving, but I recognize that one can get a DUI as much by bad luck as by irresponsible behavior. There is a growing body of research that shows that the distraction of talking on a mobile phone affects driving as or more severely as .8% blood alcohol. In other words, it takes far less booze than most people think, most of whom drive home without incident.
People always speculate about why they did or did not get a particular job. If you give someone a reason to be suspicious or cranky about your decision, he or she may learn through the discovery process that you hired someone who does not appear to be at least as qualified. That can be embarassing and expensive. Especially if the DUI conviction is not allowed into evidence on the discrimination charge your company ends up facing.
Unless the position involves driving, it's not clear to me that anything has been divulged which should reflect poorly on the person's candidacy.
There are too many things we do not know about. How long ago was the DUI? Was it a felony? Was there a related felony? Have you run a background check? Was it clean other than the DUI? What is the nature of the job? How qualified is the candidate.
The only people who do not frown on using arrests and unrelated convictions as a litmus test for hiring consideration are plaintiff's attorneys.