Ask HN: Is it acceptable to refuse to answer a question in a tech interview?
Maybe the question sounds suspiciously useful to the company?
Of course, if they ask you about how you implemented the patent protected confabulator at your current role, then there’s a reason to politely decline (and they hopefully wouldn’t hire someone who spills business secrets in an interview).
If the question is job relevant, its more complicated.
I can’t imagine a company that uses interviews as a way to solve problems for free would be in business for very long.
Cheers, M