We are called on to determine whether plaintiffs’ instant lawsuit is barred by res judicata as a result of defendants having prevailed in a prior federal lawsuit. We hold that, where the district court dismissed all plaintiff’s federal claims in advance of *375trial, and there are no exceptional circumstances that would give the federal court grounds to retain supplemental jurisdiction over the state claim, then it is clear that the federal court would not have exercised its supplemental jurisdiction over the remaining state law claims. For the reasons stated below, we find res judicata does not bar plaintiffs’ instant action, and therefore, affirm the decision of the Court of Appeals.
i
Plaintiff Pierson Sand and Gravel, Inc., commenced an action in the United States District Court for the Western District of Michigan against Pierson Township on August 3, 1989, asserting claims under §§ 107(a) and 113(f) of the federal CERCLA1 statute, as well as under the Michigan Environmental Protection Act (mepa),2 and for common-law trespass.3 Defendant Keeler Brass Company was added as a defendant in the federal action in a second amended complaint, but later dismissed without prejudice, and then again added in a third amended complaint.
Plaintiffs’ third amended complaint, filed on October 15, 1992, stated claims against the township, Keeler, and defendant Chemetron Investments, Inc., as well as several other chemical manufacturers. The action sought recovery costs for the environmental cleanup of the Central Sanitary Landfill in Macomb *376County owned by the plaintiffs. By the time plaintiffs filed the third amended complaint, they were asserting only cercla claims, and had abandoned their prior state law claims.
Also in existence at this time was the Michigan Environmental Response Act (mera),4 which forms the basis of the instant action. In 1989, when plaintiffs filed their initial complaint, the mera did not recognize a private cause of action. Subsequently, the Legislature amended the mera to recognize a private cause of action, and, at the time plaintiffs filed their third amended complaint, in October 1992, mera recognition of a private cause of action had recently taken effect. Plaintiff did not, however, include a claim under the mera in any of its federal complaints.
Following extensive procedural maneuvers, including the addition of many third-party defendants, the parties undertook discovery in the federal case and completed mediation. Cross motions for summary disposition were submitted to the court shortly before the scheduled start of trial. The district court issued an opinion and judgment granting summary judgment for defendants, ruling that the plaintiff was not entitled to recover response costs pursuant to the CERCLA on the basis of a finding that plaintiff could not prevail as a matter of law in an essential element of its claim, in that the plaintiff had not complied with the *377statutorily required National Contingency Plan (ncp), a necessary prerequisite to a cercla action.5
Plaintiff appealed to the United States Court of Appeals for the Sixth Circuit, which affirmed in .an opinion not designated for publication.6 Shortly thereafter, plaintiff instituted the instant action, seeking relief under the MERA, as well as various common-law claims for negligence, negligence per se, private nuisance, public nuisance, common-law indemnity, and common-law contribution.
The parties do not dispute that the claims and theories in the instant case arise out of the same alleged transactions and occurrences that led to the prior federal litigation. The defendants are alleged to be liable because of contamination of landfill sites during a time when hazardous substances were alleged to have been disposed there. The claims against defendants Keeler and Chemetron are based on their alleged liability for disposal, or alleged arrangement for transfer of hazardous substances, while the township’s liability is based on operating the landfill. The relief sought by the plaintiff, recovery of claimed response costs for remediation of the soil and groundwater, is the same relief sought in the federal action.
Defendants moved for summary disposition pursuant to MCR 2.116(C)(7), asserting res judicata as a bar to the instant action. Citing Sherwin-Williams Co *378v City of Hamtramck, 840 F Supp 470 (ED Mich, 1993), the Ingham Circuit Court denied defendants’ motion. Defendants appealed as of right in the Court of Appeals, which affirmed, citing 1 Restatement Judgments, 2d, § 25, comment e, illustration 10, pp 213-214.7
Defendants separately applied for leave to appeal to this Court, and this Court granted those applications and consolidated them to consider whether res judicata should operate to bar plaintiffs’ instant action. We conclude that a proper application of established principles of res judicata will not lead to a finding of such a bar.
n
Defendants-appellants present us with the single question, whether the Court of Appeals erred in determining that res judicata would not bar the plaintiffs’ instant state action.8 The Court of Appeals analyzed this issue as follows:
Defendants next argue that the doctrine of res judicata bars plaintiffs’ present lawsuit. We disagree. The federal district court that decided plaintiffs’ prior suit could have exercised pendent jurisdiction over plaintiffs’ state law claims, *379had the claims been raised before it. However, where the district court dismissed all plaintiffs’ federal claims in advance of trial, it is clear that the federal court would not have exercised its pendent jurisdiction over the remaining state law claims. See Sherwin-Williams Co v Hamtramck, 840 F Supp 470, 479 (ED Mich, 1993); see also Bell v Fox, 206 Mich App 522; 522 NW2d 869 (1994). Res judicata therefore does not bar plaintiffs’ subsequent state suit. Restatement Judgments, 2d, § 25, comment e, illustration 10, pp 213-214, see Anderson v Phoenix Investment Counsel of Boston, Inc, 387 Mass 444, 449-452; 440 NE2d 1164 (1982).
The determination whether res judicata will bar a subsequent suit is a question of law that we review de novo. Cardinal Mooney High School v Michigan High School Athletic Ass’n, 437 Mich 75, 80; 467 NW2d 21 (1991).
The Court of Appeals relied on 1 Restatement Judgments, 2d, § 25, comment e, illustration 10, pp 213-214.9
A commences an action against B in a federal court for treble damages under the federal antitrust laws. After trial, judgment is entered for the defendant. A then seeks to commence an action for damages against B in a state court under the state antitrust law grounded upon substantially the same business dealings as had been alleged in the federal action. Even if diversity of citizenship between the parties did not exist, the federal court would have had “pendent” jurisdiction to entertain the state theory. Therefore unless it is clear that the federal court would have declined as a matter of discretion to exercise that jurisdiction (for *380example, because the federal claim, though substantial, was dismissed in advance of trial), the state action is barred.
in
“The doctrine of res judicata was judicially created in order to ‘relieve parties of the cost and vexation of multiple lawsuits, conserve judicial resources, and, by preventing inconsistent decisions, encourage reliance on adjudication.’ ” Hackley v Hackley, 426 Mich 582, 584; 395 NW2d 906 (1986), quoting Allen v McCurry, 449 US 90, 94; 101 S Ct 411; 66 L Ed 2d 308 (1988). Both Michigan and the federal system have adopted a broad approach to the application of res judicata. Hackley; Rivet v Regions Bank of Louisiana, 522 US 470, 474-476; 118 S Ct 921; 139 L Ed 2d 912 (1998). As we have stated:
In Michigan, the doctrine of res judicata applies, except in special cases, in a subsequent action between the same parties and “ ‘not only to points upon which the court was actually required by the parties to form an opinion and pronounce a judgment, but to every point which properly belonged to the subject of litigation, and which the parties, exercising reasonable diligence, might have brought forward at the time.’ ” [Hackley at 585 (citations omitted).]
As a general rule, res judicata will apply to bar a subsequent relitigation based upon the same transaction or events, regardless of whether a subsequent litigation is pursued in a federal or state forum. The rule, as applied by the federal courts, has been stated as:
If a plaintiff has litigated a claim in federal court, the federal judgment precludes relitigation of the same claim in state court based on issues that were or could have been *381raised in the federal action, including any theories of liability based on state law. The state courts must apply federal claim-preclusion law in determining the preclusive effect of a prior federal judgment. [18 Moore, Federal Practice, § 131.21[3][d], p 131-50.]
We thus turn to the question whether the plaintiffs’ claims fall within one of the “special cases” contemplated in Hockley, and, in particular, within the boundaries stated in the Restatement comment.
IV
On appeal, defendants first attack the decision of the Court of Appeals as being one that ignores the longstanding rules of res judicata. We disagree, however, in that it is clear that the Court of Appeals decision reflects a cognizance of the general scope of res judicata, while relying instead on a narrow exception, that found in the Restatement comment. In view of the favor that we have traditionally shown toward a broad application of res judicata, it would be erroneous to read the Court of Appeals decision in any manner that would indicate a retreat from such a preference.10 The Court of Appeals did not depart from our consistent holdings in the area of res judicata, but instead focused solely on a narrow exception within those confines.
Turning to the exception of the Restatement comment, defendants then argue that its application should be limited solely to exceptional cases where it *382is abundantly clear that the federal court would decline to exercise its jurisdiction over state claims that were not submitted to it. We find that this case is a stellar example of one in which the Restatement comment should apply.
v
The question here is whether plaintiffs’ state claims, which were not brought with the federal action, are precluded by the doctrine of res judicata. We must remember that this doctrine is not a constitutional mandate that must be carefully construed to maintain its integrity, but only a tool created by the courts.
As we noted above, in Michigan, the doctrine of res judicata has been applied “ ‘not only to points upon which the court was actually required by the parties to form an opinion and pronounce a judgment,’ ” but applies to “ ‘every point which properly belonged to the subject of litigation, and which the parties, exercising reasonable diligence, might have brought forward at the time.’ ” Hackley, supra at 585. Thus, plaintiffs’ state claims, which could have been brought with the federal claims by supplemental jurisdiction, clearly would have been barred by res judicata if the federal court had entered a judgment on the federal claim. However, if plaintiffs had brought the state claims in the federal court, and the federal court had refused to retain jurisdiction over them when it dismissed the federal counts, then the plaintiffs would not be barred by res judicata from bringing their state claims in state court. Merry v Coast Community College Dist, 97 Cal App 3d 214, 228; 158 Cal Rptr 603 (1979). 1 Restatement Judgments, 2d, *383§ 25, comment e, p 213 essentially attempts to assure that those claims that could have been brought, but were not, receive the same treatment as if they had been brought.11 Thus, if the federal court would clearly have dismissed the state claims when it dismissed the federal claims, then the doctrine of res judicata should not apply. The goal of res judicata is to promote fairness, not lighten the loads of the state court by precluding suits whenever possible.
With the recognition of pendent (now supplemental) jurisdiction of the federal courts over state claims, there also arose a reluctance of the federal courts to address solely state matters on those occasions when the court was able to dispose of all federal claims before trial. United Mine Workers of America v Gibbs, 383 US 715; 86 S Ct 1130; 16 L Ed 2d 218 (1966).
Pendent jurisdiction [over a state claim] exists whenever there is a [federal] claim . . . and the relationship between that claim and the state claim permits the conclusion that the entire action . . . comprises but one . . . “case.” The federal claim must have substance sufficient to confer subject matter jurisdiction on the court. The state and federal claims must derive from a common nucleus of operative fact . . . such that [the plaintiff] would ordinarily be expected to try them all in one judicial proceeding .... [Pendent jurisdiction] need not be exercised in every case in which it is found to exist. It has consistently been recognized that pendent jurisdiction is a doctrine of discretion, not of plaintiff’s right. . . . Certainly, if the federal claims are dismissed before trial . . . the state claims should be *384dismissed as well . . . without prejudice and left for resolution to state tribunals. [Id. at 725-727 (citations omitted).]
Indeed, this reluctance has grown to become accepted and practiced by the vast majority of federal circuits. See, e.g., Purgess v Sharrock, 33 F3d 134 (CA 2, 1994); Tully v Mott Supermarkets, Inc, 540 F2d 187 (CA 3, 1976); Hankins v The Gap, Inc, 84 F3d 797 (CA 6, 1996).12 Accordingly, we can confidently surmise that, as a general rule, where, as in the instant case, all federal claims are resolved before trial, federal courts will decline to exercise supplemental jurisdiction over remaining state law claims, preferring to dismiss them without prejudice for resolution in the state courts.13
We hold that, when the federal claims are dismissed before trial, the federal court clearly would have dismissed the state claims if there are no exceptional circumstances that would give the federal courts cause to retain supplemental jurisdiction.
This approach closely tracks the federal rule that “in the usual case in which all federal-law claims are eliminated before trial, the balance of factors to be considered under the pendent jurisdiction doctrine-judicial economy, convenience, fairness, and comity — will point toward declining to exercise jurisdiction over the remaining state claims.” Carnegie-Mellon Univ v Cohill, 484 US 343, 350; 108 S Ct 614; *38598 L Ed 2d 720 (1988). The example given in 1 Restatement Judgments, 2d, § 25, comment e, illustration 10, p 214, also supports this approach. It provides, in pertinent part:
Therefore unless it is clear that the federal court would have declined as a matter of discretion to exercise that jurisdiction (for example, because the federal claim, though substantial, was dismissed in advance of trial), the state action is banned. [Emphasis added.]
The Restatement lists the situation we have here— where the federal claim was dismissed before trial— as an example of when it is “clear that the federal court would have declined” to retain jurisdiction of the state claim. This approach is also consistent with the manner in which other courts have applied the Restatement. See Parks v City of Madison, 171 Wis 2d 730; 492 NW2d 365 (1992); Sattler v Bailey, 184 W Va 212; 400 SE2d 220 (1990); Merry v Coast Community College, supra.
Further, this approach is supported by the comity implications of supplemental jurisdiction. Although res judicata is grounded in efficiency, finality, and fairness, application of the doctrine under circumstances involving the federal court’s supplemental (pendent) jurisdiction must also take into account the constitutional foundation of that jurisdiction. Supplemental jurisdiction raises concerns regarding comity because the doctrine is grounded in the judicial economy, convenience, and fairness to litigants of the federal court’s consideration of both federal and state claims that comprise but one “case.” Gibbs, supra at 725-726. If not for the federal question involved, the state law claims would not fall within the federal *386court’s jurisdiction. Id. Considering comity as well as general fairness, we conclude that judicial efficiency should not prevail under these circumstances.
Exceptional circumstances that would cause the federal court to retain supplemental jurisdiction might include when the defendant fails to call the court’s attention to the weakness of the federal claim before the court has invested a substantial amount of time in the case; when the supplemental claim significantly invokes questions of federal policy, Kavit v A L Stamm & Co, 491 F2d 1176, 1180 (CA 2, 1974); where the court and the litigants had expended considerable time on the supplemental claims before the federal claim was dismissed, Meyer v California & Hawaiian Sugar Co, 662 F2d 637 (CA 9, 1981); and where there have been substantial resources invested in the lawsuit towards the resolution of the dispute, and the parties are ready for trial, Newport Ltd v Sears, Roebuck & Co, 941 F2d 302 (CA 5, 1991). There are no factors in the instant case that would compel the federal court to retain jurisdiction over the state claims. While defendants point to the years of pretrial maneuvering that occurred in this case, we note that there is a good deal of accuracy to plaintiffs’ position that much of the pretrial maneuvering involved the inclusion of third-party defendants, as opposed to the expenditure of significant resources between the instant parties in preparing to litigate the underlying matter. While federal courts have recognized that, at times, the expenditure of excessive resources by the parties in preparing for trial might be sufficient to sway the courts to exercise jurisdiction over state claims even in the absence of remain*387ing federal claims,14 there appear to be no such factors in the instant case that would merit such a determination.
While we would not condone, or intend to encourage, the failure of plaintiffs to include an MERA claim in the federal action that precluded the district court from having the opportunity to decline to exercise jurisdiction, we cannot accept defendants’ invitation to extend such a failure to preclude errors in state actions on the basis of res judicata. As noted in a similar matter by the Wisconsin Court of Appeals:
Based on Gibbs and the Restatement comments and commentary, federal courts consistently have held that when a federal claim is dismissed on a motion for summary judgment, the exercise of sound discretion requires dismissal of the state claims as well, without prejudice to the plaintiff’s right to litigate them in the proper state forum. Most particularly, the Court of Appeals for the Seventh Circuit has stated that . . . “when the federal claims are disposed of before trial, the state claims should be dismissed without prejudice almost as a matter of course.” [Parks, supra at 737-738.]
We hold that, where the district court dismissed all plaintiff’s federal claims in advance of trial, and there are no exceptional circumstances that would give the federal court grounds to retain supplemental jurisdiction over the state claim, then it is clear that the federal court would not have exercised its supplemental jurisdiction over the remaining state law claims.
Accordingly, pursuant to the Restatement comment, res judicata will not act to bar plaintiffs’ claim. The decision of the Court of Appeals is affirmed.
*388Brickley, Kelly, and Corrigan, JJ., concurred with Weaver, C.J. Cavanagh, J., concurred in the result only.The Comprehensive Environmental Response, Compensation, and Liability Act, specifically, 42 USC 9607(a) and 42 USC 9613(f).
MCL 691.1201 et seq.-, MSA 14.528(201) et seq.
Pierson Sand and Gravel, Inc., was the only plaintiff in the federal action, but it is undisputed that the plaintiffs in this case, Pierson Sand and Gravel, Inc., and Central Sanitary Landfill, Inc., are identical to the plaintiff in the federal action.
Then MCL 299.601 et seq.; MSA 13.32(1) et seq. The instant action arose under the mera as amended in 1990. Subsequently, 1994 PA 451 codified the mera as part 201 of the Natural Resources and Environmental Protection Act (nrepa), MCL 324.20101 et seq.; MSA 13A.20101 et seq., effective March 30, 1995. Subsequently, the Legislature further amended the nrepa in 1995 and 1996. The version of the mera as it existed after the 1990 amendments is controlling in the case before us.
The National Contingency Plan is described at 42 USC § 9605 and is set forth at 40 CFR Part 300, et seq. That plan sets forth “procedures and standards for responding to releases of hazardous substances, pollutants, and contaminants . . . 42 USC § 9605. [United States v R W Meyer, Inc, 889 F2d 1497, 1500, n 8 (CA 6, 1989).]
Pierson Sand & Gravel, Inc v Pierson Twp, 89 F3d 835 (CA 6, 1996) (table).
Unpublished opinion per curiam, issued February 7, 1997 (Docket No. 185124).
In the Court of Appeals, defendants also claimed error in the trial court’s application of federal law, as opposed to Michigan law, in determining whether plaintiffs’ state cause of action was barred by res judicata The Court of Appeals held that federal law governs the res judicata effect of federal judgments, including those in diversity cases, in subsequent suits. Restatement Judgments, 2d, § 87, p 314; Travelers Indemnity Co v Sarkisian, 794 F2d 754, 761, n 8 (CA 2, 1986); Silcox v United Trucking Service, Inc, 687 F2d 848, 852 (CA 6, 1982). Defendants no longer claim error in this conclusion.
We note that we have often examined the Restatement of Judgments, 2d, in construing whether subsequent claims would be precluded. See, e.g., Quinton v General Motors Corp, 453 Mich 63, 99; 551 NW2d 677 (1996) (Boyle, J., concurring); Kosiel v Arrow Liquors Corp, 446 Mich 374, 379; 521 NW2d 531 (1994); Amalgamated Transit Union, Local 1564, AFL-CIO v Southeastern Michigan Transportation Authority, 437 Mich 441; 473 NW2d 249 (1991).
Likewise, we caution that it would be an error to read our decision today as a retreat from a broad application of res judicata. We recognize today only the application of an already accepted and quite narrow exception to the application of res judicata as a bar to a subsequent state action following a federal action.
As the Minnesota Supreme Court said, “it would be unfair to impose a harsher result for unappended state law claims than would have occurred had the claims been raised.” Beutz v A O Smith Harvestore Products, Inc, 431 NW2d 528, 532 (Minn, 1988).
At least one federal circuit has held that, where the federal claims are dismissed, it is an abuse of discretion on the part of the federal district court to retain jurisdiction over a novel and complex state law claim. Parker & Parsley Petroleum Co v Dresser Industries, 972 F2d 580 (CA 5, 1992).
See, e.g., Baltimore Orioles, Inc v Major League Baseball Players Ass’n, 805 F2d 663 (CA 7, 1996), and O’Connor v Nevada, 27 F3d 357 (CA 9, 1994).
See O’Connor v Nevada, n 13 supra.