Asked what about it by who? The question is too broad to admit of a proper answer. Realistically, this question would have come up during the discovery phase, at which point it would either be the subject of a motion to seal or withhold evidence (possibly without the knowledge of the counterparty, but between your attorney and the court). If it were asked out of the blue it would be objected to by your attorney, most likely; or you could plead the 5th, since answering questions about the NSL could indeed incriminate you. IANAL, mind.