
196 Mich. App. 32 (1992)
492 N.W.2d 481
CITY OF MARYSVILLE
v.
PATE, HIRN & BOGUE, INC
Docket No. 127058.
Michigan Court of Appeals.
Decided September 9, 1992, at 9:10 A.M.
Nicholson, Fletcher, West & DeGrow, P.C. (by Michael L. West), for the plaintiff.
Sullivan, Ward, Bone, Tyler, Fiott & Asher, P.C. (by Michelle A. Thomas), for the defendant.
Before: JANSEN, P.J., and MICHAEL J. KELLY and GRIFFIN, JJ.
PER CURIAM.
Plaintiff, City of Marysville, appeals as of right from a February 20, 1990, order of the St. Clair Circuit Court granting summary disposition to defendant, Pate, Hirn & Bogue, Inc., on the ground that plaintiff's claim is barred by the applicable statute of limitations. MCR 2.116(C) (7). We reverse the order of the circuit court.
*34 Plaintiff first contends that the two-year discovery rule of Dyke v Richard, 390 Mich 739; 213 NW2d 185 (1973), is the applicable limitation period in this case. Preliminarily, we must determine whether the parties' prior appeal in this case resolved this issue, thereby preventing our review under the doctrine of law of the case. See City of Marysville v Pate, Hirn & Bogue, Inc, 154 Mich App 655; 397 NW2d 859 (1986). We conclude that it did not.
The doctrine of law of the case provides that where an appellate court has ruled on a legal question and remanded a case for further proceedings, the legal question determined by the appellate court will not be determined differently in a subsequent appeal in the same case where the facts remain materially the same. Toska v Campbell, 155 Mich App 671, 674; 400 NW2d 617 (1986); Locricchio v Evening News Ass'n, 438 Mich 84, 109; 476 NW2d 112 (1991). This doctrine applies only to those questions determined by the appellate court's prior decision and to those questions that are necessary to the court's determination. Toska, p 674. The doctrine exists primarily to maintain consistency and avoid reconsideration of matters previously decided in the course of a single, continuing lawsuit. Locricchio, p 109. The doctrine merely expresses the practice of courts generally to refuse to reopen what has been decided, not a limit on their power. Id. The doctrine applies to issues resolved in interlocutory proceedings. People v Freedland, 178 Mich App 761, 770; 444 NW2d 250 (1989).
To resolve this preliminary issue, we must determine whether this Court, in Marysville, supra, specifically or necessarily determined that the applicable statute of limitations discovery period was six months rather than two years. After reviewing *35 that opinion, we conclude that this Court's prior decision did not specifically address whether a two-year or a six-month discovery period applies. Furthermore, whether the two-year or the six-month discovery period applies in the present case was not necessarily suggested by the holding in Marysville. Although this Court held that the trial court correctly applied the general malpractice statute of limitations, as opposed to Michigan's architect and engineer statute of limitations, it was not implied or necessarily suggested that the six-month discovery period applied. This Court concluded that, because further factual development was necessary regarding whether plaintiff's claim was barred by the general malpractice statute of limitations, the trial court did not err in denying defendant's motion for accelerated judgment with respect to plaintiff's malpractice claim. Id., p 661. We hold that the doctrine of law of the case does not preclude our review of this issue.
Because we have held that the doctrine of law of the case does not prevent our review of the issue now raised by plaintiff, we must determine which is the applicable discovery period under the statute of limitations. Plaintiff argues that the six-month discovery period contained in MCL 600.5838(2); MSA 27A.5838(2), effective July 9, 1975, was not yet in existence when the alleged malpractice occurred, and, therefore, the cause of action would not be barred by the six-month discovery period. Rather, plaintiff asserts that, because the alleged malpractice occurred before the effective date of the amendment of MCL 600.5838; MSA 27A.5838, the rule in Dyke, supra, controls the accrual and discovery of its malpractice claim. We agree with plaintiff.
In Dyke, the Michigan Supreme Court held that an action based on the malpractice of a state-licensed *36 person must be brought within two years of the time when that person discontinues treating or otherwise serving the plaintiff, "or within two years of the time when the plaintiff discovers, or in the exercise of reasonable diligence should have discovered, the asserted malpractice, whichever is later." Id., p 747. The preamendment version of MCL 600.5838; MSA 27A.5838 applies in cases where the alleged malpractice occurred before July 9, 1975, even though the basis of the action was not discovered until some time after July 9, 1975. Goodwin v Schulte, 115 Mich App 402, 410; 320 NW2d 391 (1982), citing Boyer v Vandenbrink, 98 Mich App 772; 293 NW2d 687 (1980).
In the present case, the alleged malpractice occurred before July 9, 1975, even though plaintiff did not discover the leakage problem at the treatment facility until October 1981. Plaintiff filed suit in August 1983, less than two years after discovering the leakage problem. As noted in a footnote to Goodwin:
Thus, MCL 600.5838; MSA 27A.5838 is both an accrual and a tolling statute. The cause of action accrues when the malpractice actually occurs. Under Dyke, supra, the limitation period embodied in MCL 600.5805; MSA 27A.5805 is tolled until the malpractice is discovered or reasonably could be discovered. With the July 9, 1975, addition of § 2 to MCL 600.5838; MSA 27A.5838, the tolling period of the statute is reduced to six months from the two years established by Dyke. Nonetheless, since the action in Boyer actually accrued before the amendment, the old tolling period from Dyke was deemed applicable. [Goodwin, p 410, n 2.]
We hold that, because plaintiff's cause of action accrued before the amendment of MCL 600.5838; MSA 27A.5838, the old tolling period from Dyke is *37 applicable. The trial court erred in granting defendant's motion for summary disposition on the basis that plaintiff failed to file its complaint within six months of discovering the alleged design defects. A question of fact remains regarding whether plaintiff should have discovered, through the exercise of reasonable diligence, the alleged malpractice before the time of actual discovery. This question was not addressed by the trial court, because plaintiff admitted that suit was not brought within six months of discovery of the alleged defects and summary disposition was granted on this basis. This question can be addressed on remand.
Plaintiff also contends that the trial court erred in dismissing its claim of breach of contract. We find this issue to be without merit, because plaintiff's claim of breach of contract was barred by the six-year statute of limitations. MCL 600.5807(8); MSA 27A.5807(8).
Affirmed in part, reversed in part, and remanded. We do not retain jurisdiction.
