FISCHEL, J.

The employee appeals from a decision in a discontinuance proceeding denying and dismissing the previously accepted claim in its entirety. We find that the administrative judge's dismissal of the accepted period of this case is error and vacate the decision on that basis.

On November 23, 1990, the employee was rear-ended at a stop light while making deliveries in the course of his employment. The accident caused the employee to have low back pain radiating into his right leg. (Dec. 12) Upon presentation of the employee's claim for compensation benefits, the insurer accepted liability and commenced payments of § 34 benefits. Two years later, on November 5, 1992, the insurer filed a request for discontinuance of benefits based on the results of an independent medical examination on October 9, 1992. After a conference on January 27, 1993, an order of modification issued which terminated § 34 benefits and ordered the insurer to pay § 35 benefits commencing from the date of that medical examination, October 9, 1992, and continuing. The employee appealed. (Dec. 3-4)

At hearing the parties opted out of the requirements of § 11A, and relied on their own medical evidence. The employee presented testimony, by way of deposition, and reports of Dr. Ronald F. Kaplan, who causally related the employee's current disability to the 1990 industrial injury. (Dec. 17) The insurer relied on the testimony, by way of deposition, and reports of Dr. James G. Wepsic, who found no causal relationship and attributed the employee's disability to long-standing degenerative disc disease. (Dec 17-18) The administrative judge concluded that, while the employee had proved that he was partially incapacitated, he had failed to prove causal relationship to the 1990 industrial accident. (Dec. 19-20) She characterized Dr. Kaplan's opinion as "conclusory," exhibiting an "absence of a medical rationale" that rendered it a "mere expression of possible causal connection." (Dec. 17) Since the employee failed on the issue of causal relationship, the administrative judge denied and dismissed the claim ab initio, discontinuing benefits retroactively to the date of the industrial accident.

The administrative judge was without authority to find that there was no causal relationship at any time between the industrial injury and the employee's disability. "[T]his case was accepted as a compensable injury by the insurer prior to hearing. Once the insurer accepted the case, it necessarily conceded [initial liability]." St. Marie v. Robert S. Brothers Lumber, 6 Mass. Workers' Comp. Rep. 155 (1992). At the time of the hearing, the issues before the administrative judge were causal relationship and extent of disability as of the time of the insurer's request for discontinuance, not causal relationship from the outset of the claim. See Welch v. A.B.F. Systems, 9 Mass. Workers' Comp. Rep. 407 (1995); King v. Morgan Family Restaurant, 3 Mass. Workers' Comp. Rep. 210, 215-216 (1989) (compensation agreement is final determination of facts material to existence of insurer's liability, but is not final determination of extent of disability).

If the medical evidence persuades the judge that disability ceased prior to the date the insurer filed its complaint to discontinue, the order of discontinuance may go back no further than the date the request was filed. See Welch v. A.B.F. Systems, supra. This is a departure from our usual rule that a cessation date be grounded in the evidence, but is appropriate, as we view it to be consistent with principles of equity, Utica Mutual v. Liberty Mutual, 19 Mass. App. Ct. 262, 267 (1985), and the beneficent design of the Act. Young v. Duncan, 218 Mass. 346 (1914); Locke, 29 Massachusetts Practice, § 29 at pp. 33-34 (1981).

We comment on one final point. The administrative judge characterized the opinion of Dr. Kaplan, which causally related the employee's disability to the industrial injury, as a "mere expression of possible causal connection" in the manner of Hachadourian's Case, 340 Mass. 81, 86 (1959), questioning its legal sufficiency to establish causal relationship. The judge so found because the opinion was conclusory. (Dec. 17) While acknowledging the province of the judge to adopt or reject whatever part of the opinion she sees fit, Amon's Case, 315 Mass. 210 (1943), it appears to us that the judge is addressing the weight which may be accorded Dr. Kaplan's opinion, rather than its legal sufficiency.

We vacate the decision and restore the employee's weekly partial incapacity benefits as per the administrative judge's conference order of January 29, 1993, payable prospectively from the date of the filing of this decision. We return the case to the senior judge for assignment to an administrative judge for hearing de novo on the employee's appeal of that conference order.

Judges McCarthy and Wilson concur.