It is common practice for any government agency, or those companies who are under contract with a government agency, to require background checks, drug screening, or confidentiality agreements of anyone they consider hiring. Primarily, this is a necessary measure to ensure the privacy and safety of the public, and those working in public service. This question commonly serves as a standard disclosure, communicating their intent to do so.

On occasion, when this question triggers discomfort when posed to a candidate, it offers the interviewer the benefit of identifying any red flags or concerns about the viability of that potential hire. Not disclosing any issues that might arise before they devote the funds to that background check suggests a disregard for the time they set aside for the interview, for their resources, and assets. So, if you do have concerns about what a background check might turn up, respectfully disclose that with transparency. Assume they'll find out anyway. This way, you'll not waste their time or money, and you'll grant yourself an opportunity to provide context to what might turn up. Take ownership of your situation every time.