*527 This legal malpractice action requires an understanding of the requirements for expert testimony under Fishman v. Brooks , 396 Mass. 643 , 487 N.E.2d 1377 (1986), and the duty of an attorney to properly advise a client when the law governing the client's case is unsettled.

Norris Marston (Norris) 4 suffered a severe brain injury after an accident at his work site, an offshore light tower. His attorneys secured a $ 7,500 lump sum settlement under the Massachusetts Workers' Compensation Act (Act), and then pursued Federal remedies, including a claim under the Jones Act, 46 U.S.C. § 30104 (2012), ultimately negotiating a $ 200,000 settlement. The plaintiff, Norris's conservator, believing these settlements were woefully inadequate in light of Norris's injuries, sued the defendant attorneys for malpractice. On the eve of trial, a judge of the Superior Court issued a number of rulings that led to the dismissal of all of Norris's claims against the attorneys. This appeal followed.

On appeal, the plaintiff principally argues that the judge (1) misapplied Fishman v. Brooks , 396 Mass. 643 , 487 N.E.2d 1377 , as to the requirements for expert testimony in a negligent settlement legal malpractice case; and (2) erred by finding that the lump sum settlement approved by the Department of Industrial Accidents (DIA) was not a final adjudication of Norris's employment status. 5 For the reasons that follow, we reverse.

Background . We recite the facts in the light most favorable to the plaintiff. See Augat, Inc . v. Liberty Mut. Ins. Co ., 410 Mass. 117 , 120, 571 N.E.2d 357 (1991). 6

*299 After a ship struck the Ambrose light tower (light tower), located approximately eight miles off the New Jersey coast, the United States Coast Guard, the owner of the light tower, became concerned about its structural integrity, and decided to completely disassemble it (project). Costello Dismantling Company, Inc., was the general contractor. Hallum Marine Construction (Hallum), one of the subcontractors, retained Norris *528 to work on the project. 7 On August 24, 2008, as Norris was cutting sections of a steel docking station attached to the light tower, the docking station came loose, striking him on the head and driving him deep into the water, where he remained for a significant period of time. Norris was diagnosed with an anoxic brain injury.

A resident of Gloucester, Norris retained local attorneys Joseph M. Orlando and Brian S. McCormick, of the firm of Orlando & Associates (collectively, attorneys). 8 The attorneys planned to seek damages exceeding $ 1,000,000 against Hallum and other parties under the Jones Act and related Federal statutes (collectively, Federal claims) 9 in the United States District Court. They decided to first pursue Norris's remedies under the Act in proceedings before the DIA. 10

1. DIA proceedings . On October 28, 2008, Attorney McCormick filed a claim with the DIA. 11 Although Hallum's workers' compensation carrier, Farm Family Casualty Insurance (Farm Family), opposed the claim, it agreed to commence voluntary wage and medical payments. See G. L. c. 152, § 19. After the contested claim was assigned to an administrative judge (AJ) for a conference, see G. L. c. 152, § 10A (1), Farm Family moved to dismiss the claim, arguing that Norris was a seaman on a vessel *529 engaged in interstate commerce (seaman), and thus ineligible to receive benefits under the Act. In a statement filed with DIA and presented to the AJ, Attorney McCormick made the following representations about why Norris was a land-based employee:

"Here, [Norris] lacked the requisite connection to the Miss Yvette [Hallum's tugboat], necessary to qualify him as a *300 seaman .... The anticipated evidence ... is as follows:

"[Norris] picked up a truck owned by the principles [ sic ] of Hallum Marine Construction, and drove to Jersey City, NJ. After waiving [ sic ] a period of time, the Miss Yvette appeared, and [Norris] boarded her. The vessel steamed 10 miles offshore, taking between 3-4 hours of time before arrival. The vessel was brought alongside the Ambrose Light Tower, where, over the following seventeen days, [Norris] spent virtually all of his work time, working with a blow torch, dismantling the structure. During this time frame, he did absolutely no work upon the Miss Yvette, but carried out all physical work activities on the structure itself. At the conclusion of his stint, the Miss Yvette carried him back to shore."

Following the conference, the AJ denied the claim for compensation, apparently concluding that Norris was a seaman. Attorney McCormick exercised Norris's right to appeal for a more complete evidentiary hearing. See G. L. c. 152, §§ 10A (3), 11. Before the hearing, Attorney McCormick settled Norris's case by lump sum agreement for $ 7,500 (Massachusetts or workers' compensation settlement). See G. L. c. 152, § 48 (1). Norris agreed to the settlement solely on the recommendation of the attorneys, who did not advise him of the potential risk to his Jones Act claims. On February 5, 2010, the AJ approved the agreement, concluding it was in Norris's best interest, and entered it as an administrative order of the DIA. 12

*530 2. Jones Act proceedings . On March 15, 2010, the attorneys filed an action under the Jones Act and general maritime law in the United States District Court for the District of Massachusetts (Federal court), raising negligence and maintenance and cure claims against Hallum (Jones Act case or claims); in addition, they asserted claims against several other parties (collectively with third-party defendants, Federal court defendants). 13 As we have noted, the generous remedies provided under the Jones Act are limited to seamen. See 46 U.S.C. § 30104 ; Morris v. Massachusetts Maritime Academy , 409 Mass. 179 , 191, 565 N.E.2d 422 (1991). "Whether under the Jones Act or general maritime law, seamen do not include land-based workers." McDermott Int'l, Inc . v. Wilander , 498 U.S. 337 , 348, 111 S.Ct. 807 , 112 L.Ed.2d 866 (1991). Attorney McCormick signed and submitted a sworn "Seaman's Affidavit" to the Federal court, averring that Norris was a "seaman." In his memorandum of law in support of his motion to amend the complaint, Attorney McCormick made the following factual representations about Norris's status:

*301 "In August of 2008, the plaintiff was hired to act as a member of the crew of the Miss Yvette, a tugboat utilized to transport barges to and from the Ambrose Lighthouse .... In the course of his work, [Norris] spent the vast majority of his time working on matters relating to the vessel, as well as the transport of materials to and from shore. He did, however, spend a small percentage of time working in actual dismantling operations on the platform itself.... [F]actually, the evidence to date supports that a substantial amount of plaintiff's duties were done upon the tender vessel, the Miss Yvette, as opposed to on the platform itself, thereby rendering him, under relevant Maritime law, a Jones Act seaman." 14

During the proceedings, Hallum and the two third-party Federal court defendants raised the specter of the possible preclusion of the Jones Act claims due to the actions and positions taken at *531 the DIA. Attorney McCormick addressed this defense in his mediation memorandum.

A one-day mediation session was held on October 17, 2011. Attorney Orlando advised Norris that if he did not take the final offer, he would lose at trial. Accordingly, Norris accepted $ 200,000 plus Farm Family's waiver of its $ 18,666.52 workers' compensation lien 15 in full settlement of his claims against all the Federal court defendants (Federal settlement). Within days, Norris retained new counsel. A petition for the appointment of a conservator on behalf of Norris was filed in the Probate and Family Court, and Norris's brother, Jonathan Marston, was appointed. The conservator sought to intervene and reopen the Federal case on behalf of Norris. His efforts were unsuccessful.

3. Legal malpractice proceedings . On March 6, 2013, the conservator filed this malpractice action in the Superior Court, asserting claims of negligence, breach of contract, and violations of G. L. c. 93A. On June 25, 2015, a judge denied the conservator's motion for partial summary judgment on the basis that he lacked an expert witness on the relevant standard of care. On October 14, 2015, Norris voluntarily supplemented his initial answers to expert interrogatories, reserving the right to supplement those answers at a later date. 16 In March, 2017, cross motions for summary judgment were denied by a second judge. Trial was scheduled for October 2, 2017.

Due to a scheduling conflict, the case was reassigned to a different session, and a third judge (trial judge) rescheduled the trial date to October 4, 2017. At a hearing *302 on October 3, 2017, the judge made a number of rulings from the bench and thereafter issued a lengthy decision that effectively ended Norris's negligence *532 and breach of contract claims. After additional proceedings, the judge extended his prior rulings to Norris's remaining G. L. c. 93A claims and dismissed the case.

Discussion . 1. Standard of review . To the extent the trial judge considered certain motions in the nature of summary judgment, we review those claims de novo, testing "whether, viewing the evidence in the light most favorable to the [conservator], all material facts have been established and the [attorneys are] entitled to a judgment as a matter of law." Augat, Inc ., 410 Mass. at 120 , 571 N.E.2d 357 . We review the remaining rulings, including the exclusion of expert testimony and the denial of Norris's motion for leave to supplement answers to expert interrogatories for abuse of discretion or other error of law. See Baudanza v. Comcast of Mass. I, Inc ., 454 Mass. 622 , 631, 912 N.E.2d 458 (2009). Finally, we review de novo pure conclusions of law in the judge's decision on motions in limine. See Commonwealth v. Spencer , 465 Mass. 32 , 46, 987 N.E.2d 205 (2013).

2. Expert testimony . The trial judge dismissed this case, first, by ruling both that Norris was required to show that the Federal settlement was unreasonable, and that Norris had failed to offer expert opinion supporting that position. The judge also ruled that Norris's theory of liability failed as a matter of law. We disagree with both rulings. This case was more than a negligent settlement case. The conservator maintained that the Massachusetts settlement had a preclusive effect on Norris's Jones Act claim, that the attorneys knew this and failed to disclose it to Norris, and that the attorneys intended to cause Norris to accept the inadequate Federal settlement to disguise their negligence.

a. Trial within a trial . Fishman permits clients claiming unreasonable settlements to proceed under one of two methodologies for trying their cases. The conservator elected to proceed under the first methodology outlined in Fishman , the so-called trial within a trial. Fishman , 396 Mass. at 647 , 487 N.E.2d 1377 . In that approach, in a single proceeding, the same jury decides first, whether the attorney was "negligen[t] in the settlement of [the client's] claim and, second, if that were established, ... whether, if the claim had not been settled, [the client] would probably have recovered more than he received in the settlement." Id . See Kiribati Seafood Co., LLC v. Dechert LLP , 478 Mass. 111 , 117, 83 N.E.3d 798 (2017). This approach is of long-standing origin, is more commonly used than the second Fishman methodology, and provides a potential opportunity *533 for greater damages. 17 See G. Jacobs & K. Laurence, Professional Malpractice § 16.40 (2007); McLellan v. Fuller , 226 Mass. 374 , 115 N.E. 481 (1917).

To prevail on his chosen approach, the conservator was required to prove that Norris probably would have obtained a better result if the Federal claim had not been settled. See *303 Fishman , 396 Mass. at 647 , 487 N.E.2d 1377 . Under that approach, the conservator would first need to establish, to the satisfaction of a fact finder, that the attorneys were negligent in recommending that Norris first enter into the workers' compensation settlement, and thereafter the settlement of the Jones Act claim. 18 Id . Second, assuming negligence was established, the "consequences," if any, of that negligence would be determined by presenting the underlying Jones Act case to the jury. See ibr.US_Case_Law.Schema.Case_Body:v1">id . ("The original or underlying action is presented to the trier of fact as a trial within a trial"); G. Jacobs & K. Laurence, Professional Malpractice § 16.40, at 388 n.4 ("the trial within a trial concept encompasses proof of damages as well as causation, since the two are inextricably linked, damages being the amount or extent of the loss caused by the defendant attorney's negligence"). See also Frullo v. Landenberger , 61 Mass. App. Ct. 814 , 818, 814 N.E.2d 1105 (2004) (fact finder essentially decides causation and damages elements of malpractice claim). In this second portion of the proceeding, Norris would be required to establish not only the liability of one or more of the Federal court defendants, but also a damages amount exceeding the amount of the *534 Federal settlement. 19 See Fishman , supra at 648, 487 N.E.2d 1377 .

The absence of an expert opinion on fair settlement value was not fatal to the conservator's legal malpractice case. Fishman teaches that while expert testimony on reasonable settlement value is admissible in this type of action, it is not required to establish the cause and extent of the client's damages. See Fishman , 396 Mass. at 647-648 , 487 N.E.2d 1377 ; Colucci v. Rosen, Goldberg, Slavet, Levenson & Wekstein, P.C ., 25 Mass. App. Ct. 107 , 116, 515 N.E.2d 891 (1987) (under Fishman , "a jury in a malpractice action can decide without expert testimony ... that the plaintiff in the malpractice action would have prevailed in his [underlying] ... tort case"). Cf. Atlas Tack Corp . v. Donabed , 47 Mass. App. Ct. 221 , 227, 712 N.E.2d 617 (1999) (contrasting Fishman ). Given the conservator's election to proceed under the first Fishman methodology, it was error for the trial judge to impose an extra burden on him -- a requirement that he show "loss/causation" through expert testimony as to reasonable settlement value. 20

b. Motion to supplement answers *304 as to reasonable settlement value . 21 After ruling that the conservator was required to provide expert opinion as to the reasonable settlement value of the Federal claims, the trial judge denied the conservator's motion to further supplement his answers to expert interrogatories by adding such an opinion. Pursuant to Mass. R. Civ. P. 26 (e) (1) (B), the conservator had timely supplemented his initial answers. At summary judgment, the second judge had rejected, without comment, the attorneys' challenge to the adequacy of Norris's expert's opinion. The deficiency later identified by the trial judge -- the lack of expert testimony on fair settlement *535 value -- was not raised until the eve of trial. 22 Up until that point, the conservator had no reason to suspect that anything might be missing from his expert disclosure.

As a result, the conservator orally requested leave to correct the deficiency, and within two days filed a written motion attaching the "missing" information. 23 See Atlas Tack Corp ., 47 Mass. App. Ct. at 224 , 712 N.E.2d 617 , quoting Mass. R. Civ. P. 26 (e) (3) (plaintiff may "file[ ] a motion to supplement its answers with the necessary information 'at any time' prior to trial"). Despite the absence of prejudice to the attorneys, the judge denied the motion. 24 Under the circumstances, this was an abuse of discretion.

3. Effect of lump sum agreement . The trial judge concluded that while the lump sum agreement was a final adjudication of Norris's claim under the Act, it did not finally adjudicate the issue of Norris's status as a nonmaritime employee for purposes of future Jones Act claims. 25 The conservator, with support from his expert witness, maintains that the agreement to accept a lump sum settlement in the DIA proceeding resulted in a "final adjudication" that potentially precluded Norris's *305 subsequent Jones Act claims. Cf. Martin v. Ring , 401 Mass. 59 , 60, 514 N.E.2d 663 (1987). We conclude that, in the context of this case, it was error to reach the *536 question whether the workers' compensation settlement had preclusive effect on the Jones Act claim. In fact, this was an issue that was not settled at the time of these proceedings. And it is the unsettled state of the law that is pertinent in assessing any negligence on the part of the attorneys.

For example, at the time of the proceedings below, the Federal courts were divided as to whether a formal award of benefits in a contested proceeding under a Federal analog to our Act, the Longshore and Harbor Workers' Compensation Act (LHWCA), barred subsequent Jones Act claims. There were a plethora of published cases in which courts, applying principles of res judicata, concluded that the Jones Act claims were in fact barred in such circumstances. 26 Here, because of the mediated Federal settlement, the Federal court never reached the estoppel issues. To date, the United States Court of Appeals for the First Circuit has yet to decide the issue. 27

Given the unsettled state of the law, the attorneys had the duty to fully disclose the potential consequences to Norris before recommending that he accept the Massachusetts settlement. See Williams v. Ely , 423 Mass. 467 , 476-477, 668 N.E.2d 799 (1996). Contrary to the trial judge's assertion, the preclusive bar had been raised in the Federal proceedings. The attorneys' failure to alert Norris to the uncertainty deprived him of the opportunity to assess the risk and was an actionable basis of negligence. See Hendrickson v. Sears , 365 Mass. 83 , 90, 310 N.E.2d 131 (1974) ("The attorney owes his client a duty of *537 full and fair disclosure of facts material to the client's interests"). The case was therefore improperly dismissed. 28

Conclusion . The judgment dismissing the conservator's complaint is reversed, and the case is remanded for further proceedings *306 consistent with this opinion. 29

So ordered .