Whether the doctrine of "primary jurisdiction" is properly characterized as a defense; Whether such a defense is waived by failure to raise it in its first responsive pleading

The court held that the doctrine of "primary jurisdiction" is not a defense, but rather a doctrine of judicial deference and discretion, a prudential doctrine, designed to accord respect to the separation of powers in the constitutional system. Because the doctrine was not a defense, it was unnecessary for defendant-Edison to have raised the issue in its first responsive pleading. Defendant supplied steam to a motel plaintiff insured. The steam was turned off for repairs to the steam lines, the motel's pipes froze and caused flooding. Plaintiff paid the claim and sought subrogation from defendant. Seventeen months after the original complaint was filed, defendant asserted the doctrine of primary jurisdiction, claimed that the motel, and defendant had a contract for the steam and the MPSC was the agency with the sole authority to assert jurisdiction over the contract dispute between itself and plaintiff. The trial court held that defendant could rely on the doctrine and granted defendant summary disposition. The Court of Appeals reversed,  holding that defendant had waived primary jurisdiction. The court agreed with the trial court and further held that the doctrine was not waivable, and that the circuit court did not err in deferring plaintiff's claim to the MPSC. The court reversed and reinstated the trial court's decision.

Justice Weaver concurred with the result of the majority opinion and the analysis of part VI.