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
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