When will Plaintiffs be able to object to the allocation of burden of proof?

The time for Plaintiffs to object to the allocation of burden of proof was at or prior to trial, when the judge could have remedied the situation if necessary. To raise it only after judgment deprives Defendant of the opportunity to meet a burden they thought was on the Plaintiffs, and leaves open the possibility of a lengthy and expensive retrial. Cf. Monsma v. Central Mutual Ins. Co., 392 F.2d 49, 52 (9th Cir.1968) (holding that rule that no party may assign as error the giving of an instruction unless he objects before the jury retires is designed to bring errors to light while there is still time to correct them without entailing costs, delay and expenditure of judicial resources occasioned by retrial).