If you have written authorization from the candidate, you can perform reference checks with their past or current employer(s). However, there are limitations to what you are legally allowed to ask, which are described by employment reference laws.
You can't ask about personal information irrelevant to the job itself, or anything protected by Title VII of the Civil Rights Act of 1964 such as:
Since state laws vary on this issue, be sure to check with your local laws to ensure compliance. As a general rule, keep your questions focused on dates and previous job titles.
Reference Checks - HR360 Unlawful Employment Practices - Law Cornell.edu
This article is for informational purposes only, is not legal, tax or accounting advice, and is not an offer to sell, buy or procure insurance. TriNet is the single-employer sponsor of all its benefit plans, which does not include voluntary benefits that are not ERISA-covered group health insurance plans and enrollment is voluntary. Official plan documents always control and TriNet reserves the right to amend the benefit plans or change the offerings and deadlines.
This article may contain hyperlinks to websites operated by parties other than TriNet. Such hyperlinks are provided for reference only. TriNet does not control such web sites and is not responsible for their content. Inclusion of such hyperlinks on TriNet.com does not necessarily imply any endorsement of the material on such websites or association with their operators.