Andover Wood Products, Inc., and its insurance carrier appeal from a decision of the Workers’ Compensation Commission, Appellate Division, affirming an award of compensation made by the Commission in response to a petition for review filed by Lenwood Dillingham. On appeal, Andover Wood Products and its insurance carrier contend, inter alia, that there was insufficient evidence to support the restoration of compensation and that .the award should have been barred by the doctrine of res judicata. We conclude that both the restoration of compensation and the decision affirming that restoration by the Appellate Division involved a misapplication of the statute governing petitions for review, 39 M.R.S.A. § 100 (Supp.1983). Accordingly, we reverse the decision of the Appellate Division.
Lenwood Dillingham was employed as a laborer for Andover Wood Products, Inc., of Andover. On or about the 22nd of May, 1981, Dillingham slipped on a piece of wood while at work, incurring an injury to his lower back. He subsequently filed a petition for compensation with the Workers’ Compensation Commission, and, following a hearing, a single Commissioner awarded him compensation based on total incapacity from June 17 to July 30, 1981, and on partial incapacity from July 31 to August 25, 1981. The Commissioner ruled that Dillingham had “failed to establish by a preponderance of the evidence a causal connection between his continuing subjective complaints of pain after August 25, 1981 and his work incident of May 22, 1981,” and that “[t]he employee has not engaged in a reasonable search for suitable work.”
A short time later, Dillingham filed a petition for review, seeking restoration of compensation based on total incapacity from August 25, 1981. In their answer, *1234Andover Wood Products and its insurance carrier raised the affirmative defense of res judicata. Following a hearing, a second Commissioner restored compensation based on total incapacity from June 28, 1982 (the date of the initial award) through the present. In his ruling, the Commissioner stated that he was “completely aware of a prior Commission decision” in this matter, but noted that his ruling was based on “different evidence of causal relationship and disability.” The Appellate Division subsequently affirmed the restoration of compensation in a Memorandum of Decision, without reaching the issue of preclusion advanced by the appellants.1
Since the inception of the Workers’ Compensation law in Maine, see P.L. 1915, ch. 295, §§ 1-51 (codified at R.S. ch. 50, §§ 1-48 (1916)), this Court has consistently held that a petition for further compensation must address a change in the petitioner’s circumstances, and that such a petition assumes that any prior decree was correct as to issues specifically ruled upon, see Canning v. State, 444 A.2d 387, 390 (Me.1982); Dufault v. Midland-Ross of Canada, Ltd., 380 A.2d 200, 203 (Me.1977); Comer’s Case, 131 Me. 386, 389, 163 A. 269, 270 (1932); Healey’s Case, 124 Me. 54, 56, 126 A. 21, 22 (1924). It is equally well established that a matter ruled upon in a prior decree will not be relitigated simply because of newly discovered evidence,2 see Canning, 444 A.2d at 390; Wood v. Cives Construction Corp., 438 A.2d 905, 908 (Me.1981); Comer’s Case, 131 Me. at 389, 163 A. at 270; Conner’s Case, 121 Me. 37, 39, 115 A. 520, 521 (1921). Of course, an employee may petition for compensation for a previously undiscovered injury that was, consequently, not ruled upon in a pri- or decree, see Canning, 444 A.2d at 390; Devoe’s Case, 131 Me. 452, 454-55, 163 A. 789, 790 (1933). No such injury is alleged in the case before us, however.
By P.L. 1981, ch. 514, § 4 (effective Sept. 18, 1981), the legislature repealed and replaced the previous section 100 of Title 39, governing petitions for review of incapacity, with a new section 100. 39 M.R.S.A. § 100 now provides that
[u]pon the petition of either party, a single commissioner shall review any compensation payment scheme required by this Act for the purposes of ordering the following relief, as the justice of the case may require: ... Increase, decrease, restoration or discontinuance of compensation .... The basis for granting relief under this section is as follows .... On the first petition for review brought by a party to an action, the commissioner shall determine the appropriate relief, if any, under this section by determining the employee’s present degree of incapacity _ For purposes of a first petition brought under this section, evidence of the employee’s medical condition at the time of an earlier determination ... is relevant only if it tends to prove the present degree of incapacity .... Once a party has sought and obtained a determination under this section, it is the burden of that party in all proceedings on his subsequent petitions under this section to prove by comparative medical evidence that the employee’s earning incapacity attributable to the work-related *1235injury has changed since that determination.
39 M.R.S.A. § 100(1)(A) & (2) (Supp.1983). It is the appellee’s position that this provision affords a single, “wide open” opportunity to relitigate any and all issues bearing upon incapacity that were addressed in a prior decree. We do not believe, however, that the legislature, by this enactment, intended to provide each petitioner with a hearing de novo on all issues previously litigated. At most, the 1981 revision of § 100 affects the burden of proving a change in earning incapacity on a party’s first petition for review.
Under the previous statute, a petitioner had to submit comparative medical evidence tending to show a change in the degree of incapacity before a compensation payment scheme would be increased or diminished. See Madore v. Bangor Roof & Sheet Metal Co., 428 A.2d 1184, 1188 (Me.1981); Marquis v. Keyes Fibre Co., 428 A.2d 69, 70 (Me.1981); Hafford v. Kelly, 421 A.2d 51, 53 (Me.1980); Nelson v. Town of East Millinocket, 402 A.2d 466, 468 (Me.1979). This requirement was seen as assuring that a prior Commission determination of the degree of incapacity would remain a final adjudication, Hayford v. Chesebrough-Ponds, Inc., 447 A.2d 480, 482 (Me.1982) (citing Haney v. Lane Construction Corp., 422 A.2d 1292, 1294 (Me.1981)).
Under the new statutory scheme, the evidentiary burden upon first-time petitioners for review has been eased. Nevertheless, we do not construe the evidentiary provisions contained in section 100 as affording a hearing de novo to the petitioner on the previously decided issue of causation. We find nothing in the statutory language that would cause us to alter our view, expressed in Canning, that
the commission like any adjudicative body has a legitimate interest in bringing litigation before it to an eventual end, and liberal though the standard of pleading must be, the commission may properly dismiss a case if the pleadings themselves, after ample opportunity to amend, still show as a matter of law that there is no cognizable issue.
444 A.2d at 390 (citation omitted).
In the case before us, Lenwood Dill-ingham applied for and received an award of compensation for injuries incurred while working for the respondent, Andover Wood Products, Inc. The award of compensation was based, in part, on a finding that the employee’s incapacity “continued until August 25, 1981,” but that “[t]he employee failed to establish by a preponderance of the evidence a causal connection between his continuing subjective complaints of pain after August 25, 1981 and his work incident of May 22, 1981.” His subsequent petition for review alleged no change in his circumstances, but once again he sought compensation for the same continuing subjective complaints of pain and on that basis alleged total incapacity after August 25, 1981. The issue whether those same continuing subjective complaints of pain had any causal connection to his work incident of May 22, 1981 had already been decided adversely to him in the previous proceeding, and was therefore res judicata. The prior adjudication that the complaints after August 25, 1981 were not causally related to the work incident of May 25, 1981 required the Commission to deny Dilling-ham’s petition for review.
The entry is:
Judgment reversed.
Remanded to the Appellate Division for entry of judgment remanding the case to the Commission with directions to deny the petition for review.
McKUSICK, C.J., and NICHOLS, ROBERTS and WATHEN, JJ., concurring.
. We note that the Appellate Division made no mention of this issue in its decision. However, the defense of res judicata was raised by the respondents in their answer to the petition for further compensation, which was part of the record available to the Appellate Division. Moreover, no one on appeal has argued that the preclusion issue was not before the Division. Given the posture of this case, we feel that a disposition by way of Memorandum of Decision was an inadequate response to the issues raised herein.
. By statutory enactment, the legislature has recently generated an exception for “newly discovered evidence which by due diligence could not have been discovered prior to the time the [initial] payment scheme was initiated or prior to the hearing on which the award or decree was based.” 39 M.R.S.A. § 99-C (Supp.1983). No such discovery was alleged or proven in the case at bar.