Rule 9(b) explicitly recognizes an exception for allegations of fraud and mistake, where a higher standard of particularity is required. Rule 8(f), stating that all pleadings shall be construed so as to do 'substantial justice,' may be read as requiring judges to exercise some degree of discretion rather than invariably applying the general rule of notice pleading. The Rules provide for a 'motion for more definite statement' as a formal method of challenging a pleading that is 'so vague or ambiguous that a party cannot reasonably be required to frame a responsive pleading.' Fed.R.Civ.P. 12(e). This Rule authorizes the court, upon failure to obey its order for a more definite statement, to 'strike the pleading to which the motion was directed or make such order as it deems just.' Id. This Rule has been invoked infrequently. More often, a court concluding that a complaint fails particularity requirements either enters an interlocutory order dismissing the complaint, but allowing leave to amend within a specified time, or allows leave to amend and defers ruling on the motion to dismiss. Either type of order has an effect closely analogous to that of an order pursuant to Rule 12(e) that unless a more ...