We transferred this case from the Appeals Court to consider whether a lawful visitor may recover damages for personal injuries caused by a breach of the implied warranty of habitability. Charles M. Scott (Scott) suffered injuries while visiting an apartment leased by his friend from the defendants, Stuart and Ellen Garfield, when a railing on a second-floor porch gave way and he fell to the ground. Judgment entered for Scott on his claim of breach of the implied warranty of habitability, and the defendants appealed. Because we conclude that a lawful visitor may recover damages for personal injuries caused by a breach of the implied warranty of habitability, that the judge neither erred in finding that the loss of evidence by the defendants constituted spoliation nor abused his discretion in imposing sanctions therefor, and that the judge did not abuse his discretion in excluding from evidence the amounts of money paid by Scott’s health insurer toward his medical bills, we affirm the judgment.
1. Background. We present the essential background and facts, reserving some details for our discussion of the issues raised.
*792In 1992, the defendants bought a three-story house in Lynn. The defendants resided on the first floor. In 1993, they let the second-floor apartment, which included a porch,3 to the plaintiffs’ friend, Sherry Baker.4 Before the defendants leased the second-floor apartment to Baker, the department of public health of Lynn inspected it and issued a certificate of occupancy. The defendant Stuart Garfield was present on the second-floor porch on several occasions after 1993. He was a social guest of Baker at times, and he also had access to the porch annually in order to clean the gutters. In 1996, after being informed that a section of railing on one side of the porch was loose, Garfield repaired it. He made no repairs to the section of railing at the other side of the porch. In 2000, Garfield told Baker that he planned to repair the porches on the house, including the second-floor front porch. No repairs were made, however, before the date when Scott was injured. In 2002, Baker gave notice that she intended to terminate her lease and move out.
On July 20, 2002, the plaintiffs planned to help Baker pack for her upcoming move. Earlier in the day, Scott had consumed a glass of wine with lunch at his home. He and his wife then went to Baker’s apartment, where several other people were helping. Scott drank a beer while socializing with some of the other guests, and opened another beer when he began to help pack. He took a rug onto the porch to shake it out, and leaned over the section of railing on the other side of the porch from where Garfield had made a repair in 1996. As he stood up, the railing gave way and Scott fell to the ground, seriously injuring his shoulder.
An attorney who represented Scott made a telephone call to Garfield eleven days after the accident and sought to have him preserve the railing. Garfield did so. The attorney did not, however, ask Garfield to preserve the columns on the porch to which the railing had been attached. During the following month, *793Garfield had a contractor, who had been performing work elsewhere at the house, perform repair work on the second-floor porch. The contractor removed the two columns to which the railing had been attached and discarded them.
The plaintiffs commenced an action in the Superior Court, asserting claims for negligence and breach of the implied warranty of habitability, as well as a separate claim by Pamela Scott for loss of consortium.5 The defendants raised as a defense that, due to his alcohol consumption, Scott had been comparatively negligent. The case was tried to a jury.
The jury returned special verdicts in favor of Scott, on his claims of negligence and breach of the implied warranty of habitability, in favor of Pamela Scott, on her claim for loss of consortium, and in favor of the Garfields on their comparative negligence defense, finding that Scott had been twenty per cent comparatively negligent. Mass. R. Civ. P. 49 (a), 365 Mass. 812 (1974). Because judgment entered for Scott on his claim of breach of the implied warranty of habitability (rather than his claim for negligence), he recovered $450,000, the full amount of damages found by the jury with no reduction for the jury’s finding of comparative negligence. Pamela Scott recovered damages in the amount of $4,000 on her loss of consortium claim. The defendants appealed, and we transferred the case to this court on our own motion.
2. Discussion, a. Implied warranty of habitability. The defendants moved for a directed verdict, Mass. R. Civ. P. 50 (a), 365 Mass. 814 (1974), and for judgment notwithstanding the verdict, or in the alternative for a new trial, Mass. R. Civ. P. 50 (b), as amended, 428 Mass. 1402 (1998), on the breach of implied warranty of habitability claim, on the ground that Scott was a guest rather than a tenant and therefore could not recover under the implied warranty of habitability. The judge denied the motions.6 The defendants contend that the judge erred in denying their *794motions because our case law has not recognized the right of a guest of a tenant to recover under the warranty. For the reasons that we now set forth, we conclude that a lawful visitor may recover for personal injuries caused by a breach of the implied warranty of habitability.
The implied warranty of habitability, as it has developed in our decisions, is a multi-faceted legal concept that encompasses contract and tort principles, as well as the State building and sanitary codes. Although the warranty itself arises from the residential leasing contract between landlord and tenant, we have imposed a legal duty on the landlord, in the form of an implied agreement, to ensure that the dwelling complies with the State building and sanitary codes throughout the term of the lease. See Crowell v. McCaffrey, 377 Mass. 443, 451 (1979). See also Doe v. New Bedford Hous. Auth., 417 Mass. 273, 281 (1994) (minimum standards of warranty of habitability measured by applicable State building and sanitary codes); Boston Hous. Auth. v. Hemingway, 363 Mass. 184, 199 (1973) (“This warranty [insofar as it is based on the State Sanitary Code and local health regulations] cannot be waived by any provision in the lease or rental agreement”). To the extent that a residential lease is a contract between landlord and tenant, there is no question that only a tenant (and not a guest) can recover for economic loss caused by a breach of the implied warranty of habitability. See, e.g., Cruz Mgt. Co. v. Thomas, 417 Mass. 782, 787 (1994).
The warranty also sounds in tort, and we have recognized that a tenant may recover damages for personal injuries caused by a breach. See Crowell v. McCaffrey, supra (implied warranty of habitability “carries with it liability for personal injuries caused by a breach”). Cf. Correia v. Firestone Tire & Rubber Co., 388 Mass. 342, 353 (1983) (recognizing product liability claims for personal injuries based on breach of warranty sound essentially in tort).
Our conclusion that lawful visitors, like tenants, may recover for personal injuries caused by breach of the implied warranty of habitability rests, in part, on the expectation that a tenant might invite a guest into his home, and the concomitant expectation that the tenant’s home must be safe for a guest to visit — which together go to the very heart of the landlord’s contractual *795obligation to deliver and maintain habitable premises that comply with the building and sanitary codes. Our conclusion is consistent with the State sanitary code itself, which provides that the purposes of the minimum standards of fitness for human habitation are to “protect the health, safety and well-being of the occupants of housing and of the general public” (emphasis added). 105 Code Mass. Regs. § 410.001 (1997). A lawful visitor of an “occupant of housing” plainly comes within the scope of persons intended to be protected and therefore also within the ambit of the implied warranty of habitability while on the rented premises.
Moreover, we have long since eliminated much of the legal significance attached to the question of status in our tort law. See Mounsey v. Ellard, 363 Mass. 693 (1973) (doing away with distinctions between categories of licensee and invitee and holding that landowner owes duty of reasonable care to all lawful visitors). A tenant’s guest may recover damages from a landlord for personal injuries caused by negligent maintenance of the premises rented to the tenant. See Young v. Garwacki, 380 Mass. 162, 168 (1980). Logic, therefore, compels our conclusion that a lawful visitor may also recover for personal injuries caused by a breach of the warranty of habitability. To decide otherwise would create or maintain a type of distinction based on status that we long ago rejected. It would not stand to reason that where a tenant and a lawful visitor both suffered injuries on the tenant’s rented premises, caused by the same significant defect in violation of the sanitary code, the tenant might recover on a breach of warranty claim, while the tenant’s guest could recover only in negligence, thus subjecting only the guest to a comparative negligence defense. See Correia v. Firestone Tire & Rubber Co., supra (comparative negligence statute, G. L. c. 231, § 85, not applicable to breach of warranty claim).7
Our holding also accords with the Restatement (Second) of *796Property (Landlord and Tenant) § 17.6 (1977), insofar as it provides:
“A landlord is subject to liability for physical harm caused to the tenant and others upon the leased property with the consent of the tenant or his subtenant by a dangerous condition existing before or arising after the tenant has taken possession . . . and the existence of the condition is in violation of: (1) an implied warranty of habitability; or (2) a duty created by statute or administrative regulation.”
Turning to the issues in this case, there was no error in the denial of the defendants’ motions for a directed verdict and for judgment notwithstanding the verdict. Based on the evidence, the jury reasonably could have found that the condition of the porch railing did not comply with the minimum standards required by the building and sanitary codes, in breach of the implied warranty of habitability, and that Scott suffered injuries as a result when the defective railing gave way.
The defendants also argue that the judge erred in failing to instruct the jury that they must find, as a threshold question, that the defendants had notice of the defect or violation giving rise to the breach of the implied warranty of habitability.8 We need not decide whether notice is necessary with respect to the implied warranty, see note 8, supra, because the jury returned special verdicts in favor of Scott on both his negligence and breach of warranty claims. The jury’s finding of negligence, which we conclude was fully supported by the evidence, indicates that the jury found the defendants had notice of the defective railing and failed to exercise reasonable care to repair it.9
*797The defendants further contend that the judge erred in failing to instruct the jury that they must find, as a threshold matter, that the porch was vital to the use of the demised premises in order to conclude that there was a breach of the implied warranty of habitability. This argument is unavailing where our decision in Crowell v. McCaffrey, 377 Mass. 443, 451 (1979), stated that the implied agreement by a landlord to ensure that a rented unit complies with minimum standards prescribed by building and sanitary codes extends to a porch that is part of a rented unit.
b. Spoliation of evidence. Before the close of evidence in the plaintiffs’ case, the judge held an evidentiary hearing outside the presence of the jury to consider the issue of spoliation of evidence, which the plaintiffs raised by a motion in limine seeking to preclude the defendants from offering evidence related to the discarded porch columns. Finding that Garfield had been negligent in the loss of the columns as evidence, and that the loss amounted to spoliation, the judge allowed the motion. The judge ruled that, as a consequence, the defendants would be precluded from presenting any evidence relating to the columns, that the plaintiffs would be permitted to inquire as to the unavailability of the columns, and that the jury would be instructed that they could draw an adverse inference because of the unavailability of the evidence.
The defendants argue that the judge erroneously shifted the burden of proof to them, that he erred in finding that the loss of the columns amounted to negligent spoliation, and that he abused his discretion in imposing sanctions therefor. The judge neither erred nor abused his discretion.
*798“The destruction of relevant evidence . . . has a pernicious effect on the truth-finding function of our courts.” Fletcher v. Dorchester Mut. Ins. Co., 437 Mass. 544, 553 (2002). The doctrine of spoliation permits the imposition of sanctions and remedies where a litigant or its expert negligently or intentionally loses or destroys evidence that the litigant (or expert) knows or reasonably should know might be relevant to a possible action, even when the spoliation occurs before an action has been commenced.10 Kippenhan v. Chaulk Servs., Inc., 428 Mass. 124, 127 (1998). Cf. Wiedmann v. Bradford Group, Inc., 444 Mass. 698, 704-707 (2005) (no abuse of discretion in imposition of sanctions for spoliation where plaintiff prejudiced by failure of defendant former employer, despite notice and statutory duty, to maintain plaintiff’s employment records); Keene v. Brigham & Women’s Hosp., Inc., 439 Mass. 223, 227, 233-237 (2003) (doctrine of spoliation applicable where defendant hospital negligently lost or destroyed medical records essential to plaintiffs malpractice claim; defendant should have been aware of a likely claim at least as early as time that it filed notice of potential claim with insurer). “[Ojnce a ‘litigant or its expert knows or reasonably should know that the evidence might be relevant to a possible action,’ we have imposed a duty to preserve such evidence in the interests of fairness.” Fletcher v. Dorchester Mut. Ins. Co., supra at 550, quoting Kippenhan v. Chaulk Servs., Inc., supra. “The threat of a lawsuit must be sufficiently apparent, however, that a reasonable person in the spoliator’s position would realize, at the time of spoliation, the possible importance of the evidence to the resolution of the potential dispute.” Kip-penhan v. Chaulk Servs., Inc., supra.
“Massachusetts affords a greater range of remedies for spoliation than the majority of jurisdictions, which limit relief to *799peraiitting an adverse inference against the responsible party.” Gath v. M/A-Com, Inc., 440 Mass. 482, 488 (2003). We have held that a judge may exclude evidence to remedy unfairness caused by the destruction or alteration of evidence by a party to litigation or by persons affiliated with a party. Fletcher v. Dorchester Mut. Ins. Co., supra, and cases cited. “The spectrum of remedies includes allowing the party who has been aggrieved by the spoliation to present evidence about the preaccident condition of the lost evidence and the circumstances surrounding the spoliation.” Gath v. M/A-Com, Inc., supra.
Once the plaintiffs produced evidence sufficient to establish certain preliminary facts, the judge did not abuse his discretion in conducting an evidentiary hearing where the burden of proof was on the defendants, who, as the alleged spoliators, were in a better position to prove that there had been no fault in their failure to preserve the columns as evidence. See Nally v. Volkswagen of Am., Inc., 405 Mass. 191, 198-199 (1989). Nor was there error in the judge’s finding that the loss of the columns amounted to negligent spoliation. There was no factual dispute that Garfield, as the landlord, had been in control of the columns after the accident, and that at the time when the columns were discarded, Garfield knew that he would likely be involved in litigation. In these circumstances, he should have also recognized the logical connection between the columns and the railings such that he reasonably should have appreciated the possible importance of the columns as evidence in such litigation. On the basis of these uncontested facts, Garfield had a duty to preserve the columns. Fletcher v. Dorchester Mut. Ins. Co., supra. The judge also correctly rejected the defendants’ contention that Garfield could not have been negligent in the loss of the columns where Scott’s attorney specifically requested that the railing be preserved but made no comparable request as to the columns. The railing was no longer attached to the porch and was on the ground, which presumably was why Scott’s counsel specifically requested that it be retained. The columns, however, remained attached and integral to the structure of the porch, and did not appear to be in imminent danger of being discarded. Had the defendants provided notice to the plaintiffs’ counsel of their intention to repair the porch, their counsel would have been in a position to make a *800comparable request that the columns be preserved. The sanction imposed by the judge was proper, given the finding that spoliation occurred.
c. Medical bills. Just prior to trial, the judge denied a motion in limine made by the defendants that sought to limit the jury’s consideration of Scott’s medical bills to the amounts actually paid to his health care providers, rather than the amounts billed by those health care providers. At trial, the judge overruled the defendants’ objection to the introduction in evidence of the medical bills with the amounts paid having been redacted, and denied a subsequent request by the defendants’ counsel for a preliminary ruling that would have allowed the defendants to attack the credibility of Scott’s testimony as to the amounts of medical expenses he had incurred. The defendants argue that the amounts actually paid to the health care providers toward the total amounts billed should not have been excluded from evidence, because such evidence, in addition to the total amounts of money billed by the providers, would have been relevant to the jury’s determination of Scott’s reasonable medical expenses.
“A plaintiff who has suffered physical injury through the fault of a defendant is entitled to recover for . . . reasonable expenses incurred by him for medical care and nursing in the treatment and cure of his injury .... The measure of damages is fair compensation for the injury sustained.” Rodgers v. Boyn-ton, 315 Mass. 279, 280 (1943). General Laws c. 233, § 79G, provides that bills for medical services “shall be admissible as evidence of the fair and reasonable charge for such services.” Section 79G further provides that it does not, by its own provisions, limit the right of a party to summon a provider of medical services for the purpose of cross-examination with respect to the bill.
Moreover, under the “collateral source rule,” we have held that a defendant may not show that a plaintiff has received other compensation for his injury from some other source. Corsetti v. Stone Co., 396 Mass. 1, 16-17 (1985). “The rationale behind this so-called ‘collateral source rule’ is that the receipt of such income does not lawfully reduce the plaintiffs’ damages, ‘yet jurors might be led by the irrelevancy to consider plaintiffs’ claims unimportant or trivial or to refuse plaintiffs’ verdicts or reduce them, believing *801that otherwise there would be unjust double recovery.’ ” Id. at 17, quoting Goldstein v. Gontarz, 364 Mass. 800, 809 (1974).
Here, the judge properly excluded from the jury’s consideration the amounts paid to Scott’s health care providers. The collateral source rule required that the amounts actually paid to the health care providers by the health insurer be redacted on the medical bills admitted in evidence.11 In any event, there could be no abuse of discretion here. Despite the defendants’ argument that the jury, in determining Scott’s reasonable medical expenses, should have been allowed to consider, in addition to the amounts billed, the amounts actually accepted by the health care providers as full payment, the defendants made no evidentiary proffer, i.e., a showing that the health care providers had agreed to accept as full payment some amount less than the amount billed, that would have laid the foundation for such a challenge to the application of the collateral source rule.
Nor was it error for the judge to instruct the jury that, “if the medical, hospital, rehabilitation, or physical therapy expenses were paid by a third party such as a medical insurance company or a health maintenance organization, that party can seek reimbursement from any amount paid from any judgment you may award.” The judge’s instruction correctly stated the law under the medical lien statute, G. L. c. Ill, § 70A. Nothing about the judge’s statement to the jury suggested that a third source had, in fact, paid Scott’s medical bills or that a medical lien existed. When considered in the context of an earlier jury instruction that the judge gave during the trial, where, in response to a requested question submitted by a juror whether Scott had health insurance, the judge declined the request and instructed the jury not to consider the issue of insurance in their deliberations, the judge’s instruction here was remedial in nature. The question from the juror made apparent that the issue whether Scott had health insurance had already entered into at least one juror’s *802consideration during the trial, and the judge’s instruction at that time, together with the statement that the defendants challenge here, adequately addressed the subject.
3. Conclusion. For the foregoing reasons, we affirm the judgment entered in this case.
So ordered.
The porch was located at the front of the house, directly above the first-floor porch, and was covered by a roof, which was held up by three columns. There were two sections of wooden railing, consisting of a top rail and a bottom rail, between which stood balusters. The sections of railing were attached to the columns at the far ends of the porch, and to either side of the column at the center of the porch.
Baker initially had a cotenant, who moved out in 1998.
The plaintiffs also asserted a claim against the defendants pursuant to G. L. c. 93A, § 9. The docket indicates that the judge dismissed this claim because the defendants were owner-occupants of the three-family dwelling and were therefore not subject to G. L. c. 93A.
The judge also denied a motion by the plaintiffs to set aside the jury’s finding of comparative negligence.
We recognize that the inapplicability of comparative negligence as a defense to a breach of warranty of habitability claim may not relieve a tenant or a lawful visitor of his or her legal responsibility to act reasonably toward a defect on the premises. Cf. Correia v. Firestone Tire & Rubber Co., 388 Mass. 342, 356 (1983) (consumer’s own negligence does not prevent recovery except where consumer unreasonably uses product that he knows to be defective and dangerous).
Where a tenant seeks to recover for economic loss under the warranty of habitability, we have held that the applicable standard is one of strict liability, rather than one of negligence (which would require that the landlord had notice of the defect). See Berman & Sons v. Jefferson, 379 Mass. 196, 198-204 (1979). We have left open the question whether, where a tenant (or, as here, a lawful visitor) seeks to recover for physical injuries caused by a breach of the warranty, the standard is one of negligence, as provided by the Restatement (Second) of Property (Landlord and Tenant) § 17.6 (1977) (requiring that landlord have notice of defect or code violation during the term of the lease), or strict liability. We need not decide the question today, because, as discussed infra, it does not affect the disposition of this case.
We have previously noted with approval the practice of charging the jury *797with special verdicts in similar circumstances. See Young v. Garwacki, 380 Mass. 162, 164 n.1 (1980) (judge instructed jury considering negligence claim by guest of tenant who fell from porch to find whether landlord owed implied duty of care in order to obviate need for new trial if appellate court were to decide on appeal of case that landlords owed such a duty). Here, the judge followed the practice by charging the jury as to both negligence and breach of the warranty of habitability and including special questions on both theories. However, the judge did not put the special questions to the jury in a proper sequence. It would have been better to ask the jury to determine first whether the landlord had breached the implied warranty of habitability, and then whether the landlord had been negligent and whether Scott had been comparatively negligent.
To the extent that any discrepancy exists between the standard expressed in Kippenhan v. Chaulk Servs., Inc., 428 Mass. 124, 127 (1998) (“if a litigant or its expert knows or reasonably should know that the evidence might be relevant to a possible action”), and Keene v. Brigham & Women’s Hosp., Inc., 439 Mass. 223, 233-237 (2003) (“evidence known to be relevant”), we need not resolve it here because, as discussed infra, the judge properly found not only that Garfield reasonably should have known that the columns might be relevant to possible litigation, but also that he actually did appreciate the likely relevance of the columns to such litigation.
Although the jury still would not have been able to consider, in determining Scott’s reasonable medical expenses, any difference between the amounts billed by his health care providers and the amounts accepted by those providers as full payment, the defendants nonetheless could have instead sought to challenge the reasonableness of the amounts billed (in and of themselves) by summoning Scott’s medical providers for cross-examination with respect to the bills. G. L. c. 233, § 79G.