Because of various difficulties in accounts of lying and related phenomena, I've been drawn to the simple theory on which it's always morally wrong to assert falsehoods, though of course if one is justified in believing the falsehood, one isn't culpable (and it's not lying then). But Heath White's argument which I reference in this comment suggests a pretty decisive argument to the contrary. Suppose that my daughter justifiably asserted to her brother: "Daddy won't play Monopoly with us tonight." It is within my power to make this false by playing Monopoly with the kids. But if I were to make it false, then on the view in question it would be the case that my daughter did something morally wrong. And surely I have a significant moral reason to avoid bringing it about that my child did something wrong, even if it would only be inculpably wrong and my bringing it about would not be intentional.