Montalvo, objecting to sub-paragraph (3), argued that: even as amended, this instruction tells the jury that if they are not able to make either an apportionment or a rough apportionment, they must divide the damages equally. . . . [However,] [u]nder [ Matsumoto v. Kaku, 52 Haw. 619 [629], 484 P.2d 147 (1971)], the situation of a single accident going to trial where there are pre-existing medical conditions either resulting from a diseased condition or otherwise, we then find that the [s]upreme [c]ourt very specifically said that if they are unable to make either an apportionment or rough apportionment, that the jury should then give one hundred percent of the damages. On the other hand, the City objected because the court redacted references to post-accident incidents:

The rationale of these cases is based on the unfairness of the imposition of the burden of proof on the innocent victim as opposed to the defendant. Also, where the negligent infliction of injury aggravates a pre-existing condition or disease, and no apportionment is possible, it has been held that the defendant is liable for the entire damage, i. e. Newbury v. Vogel, 151 Colo. 520, 379 P.2d 811 (1962); (pre-existing arthritic condition); Kawamoto v. Yasutoke, 49 Haw. 42, 410 P.2d 976 (1966) (possible prior back problems and an arthritic condition; Blaine v. Byers, 91 Idaho, 665, 429 P.2d 397 (1967) (pre-existing arthritic condition); Matsumoto v. Kabu, 52 Haw. 629, 484 P.2d 147 (1971) (pre-existing back pain); Wise v. Carter, 119 So.2d 40 (Fla.App. 1960) (prior injury). The justifications for this principle are, however, different from that used in the multi-collision cases.

In such cases, even though a portion of the present and future disability is directly attributable to the preexisting condition, the defendant whose act of negligence was the cause of the subsequent act is responsible for the entire damage.See Owen v. Dix, 210 Ark. 562, 196 S.W.2d 913, 915 (1946) (when defendant's negligence aggravates a dormant or diseased condition, defendant is liable for entire damages, notwithstanding the dormant or diseased condition); Newbury v. Vogel, 151 Colo. 520, 379 P.2d 811, 813 (1963) (when a preexisting condition is aggravated and apportionment between the preexisting condition and the aggravating event cannot be made, the defendant who caused the aggravating event is responsible for the entire damage); Winn-Dixie Stores, Inc. v. Nafe, 222 So.2d 765, 766 (Fla.Dist.Ct.App. 1969) (when the jury cannot apportion damages between an aggravating event and a preexisting disease, all damages are assessed to tortfeasor); Matsumoto v. Kaku, 52 Haw. 629, 484 P.2d 147, 149 (1971) (when a plaintiff with a diseased condition suffers injuries due to defendant's negligence and damages between the diseased condition and the defendant's negligence cannot be apportioned, the defendant is liable for the entire damage); Blaine v. Byers, 91 Idaho 665, 429 P.2d 397, 405-06 (1967) (worsening of plaintiff's preexisting arthritic condition due to defendant's negligent act is attributable to defendant when apportionment between the preexisting arthritic condition and the worsened arthritic condition cannot be made); Bushong v. Kamiah Grain, Inc., 96 Idaho 659, 534 P.2d 1099, 1101 (1975) (defendant who aggravates a plaintiff's preexisting condition through an act of negligence is liable for the entire damage if apportionment between the preexisting condition and the defendant's negligence is not possible); Becker v. D E Distributing Co., 247 N.W.2d 727, 731 (Iowa 1976) (when a preexisting condition is aggravated and no apportionment can be made between the preexisting condit

Hylton v. Wade, 29 Colo. App. 98, 478 P.2d 690 (1970); Moyer v. Merrick, 155 Colo. 73, 392 P.2d 653 (1964); Intermill v. Heumesser, 154 Colo. 496, 391 P.2d 684 (1964); Koch v. Stephens, 37 Colo. App. 561, 552 P.2d 525 (1976), reversed sub nom. Stephens v. Koch, 192 Colo. 531, 561 P.2d 333 (1977); Hildyard v. Western Fasteners, Inc., 33 Colo. App. 396, 522 P.2d 596 (1974); Brittis v. Freemon, 34 Colo. App. 348, 527 P.2d 1175 (1974); Brooks v. Reiser, 483 P.2d 389 (Colo.App. 1971).Matsumoto v. Kaku, 52 Haw. 629, 484 P.2d 147 (1971); Bachran v. Morishige, 52 Haw. 61, 469 P.2d 808 (1970); Kawamoto v. Yasutake, 49 Haw. 42, 410 P.2d 976 (1966); Bushong v. Kamiah Grain, Inc., 96 Idaho 659, 534 P.2d 1099 (1975); Blaine v. Byers, 91 Idaho 665, 429 P.2d 397 (1967). Opposing the Bigleys' view, Craven argues that an injured party is not entitled to a Newbury-like instruction unless that party shows that his disability cannot be apportioned based on the evidence presented at trial.

Findings of the trial court will not be disturbed unless clearly erroneous. Matsumoto v. Kaku, 52 Haw. 629, 484 P.2d 147 (1971). A finding of fact is clearly erroneous when a reviewing court is driven irrefragably to the conclusion that an objective review of the evidence would result in a different conclusion.

The legal substance of Instruction no. 40 was approved by this court in Blaine v. Byers, 91 Idaho 665, 429 P.2d 397 (1967). See, Newbury v. Vogel, 151 Colo. 520, 379 P.2d 811 (1963); Bennett v. Messick, 76 Wn.2d 474, 457 P.2d 609 (1969); Matsumoto v. Kaku, 52 Haw. 629, 484 P.2d 147 (1971). See also, Restatement Torts 2d § 461 (1965).

The justification for this rests upon the fact that a choice must be made, as to where the loss due to failure of proof shall fall, between an entirely innocent plaintiff and defendants who are clearly proven to have been at fault and to have done him harm. Cases adopting this principle include Matsumoto v. Kaku, 484 P.2d 147 (Sup.Ct. Hawaii 1971); Graham v. Roberts, 142 U.S. App. D.C. 305, 441 F.2d 995 (1970); Hylton v. Wade, 29 Colo. App. 98, 478 P.2d 690 (1970); Blaine v. Byers, 91 Idaho 665, 429 P.2d 397 (1967); Newbury v. Vogel, 151 Colo. 520, 379 P.2d 811 (1963). We think the principle a sound one in the circumstance here presented of malpractice in the treatment of a preexisting disease or condition. Cf. NOPCOChemical Div. v. Blaw-Knox Co., 59 N.J. 274, 284-285 (1971).

In the instant case, where the Victim had a pre-existing condition at the time of the incident, where the evidence indicates that a significant worsening of the pre-existing condition was caused by the Defendant, where there is no expert medical opinion or other competent medical evidence upon which an apportionment can be made, then the Defendant is liable for the entire amount of the damages or losses incurred as a direct result of the incident. Kawamoto v. Yasutake, 49[ ] Haw. 42 (1966) ; Matsumoto v. Kaku, 52 Haw. 629 (1971).4.

2001) (citing Newbury v. Vogel, 379 P.2d 811, 813 (Colo. 1963); Lovely v. Allstate Ins. Co., 658 A.2d 1091, 1092 (Me. 1995); David v. DeLeon, 547 N.W.2d 726, 730 (Neb. 1996); Bigley v. Craven, 769 P.2 892, 898 (Wyo. 1989)); Fosgate v. Corona, 330 A.2d 355, 358 (N.J. 1974) (citing Matsumato v. Kaku, 484 P.2d 147 (Sup.Ct. Hawaii 1971); Graham v. Roberts, 441 F.2d 995 (U.S.App.D.C. 1970); Hylton v. Wade, 478 P.2d 690 (Colo.App. 1970); Blaine v. Byers, 429 P.2d 397 (Idaho 1967); and Newbury v. Vogel, 379 P.2d 811)). Many of the cases cited made no mention of burden-shifting, however, but expressly dealt with jury instructions when the harm caused by a preexisting injury and aggravation was indivisible. Accord Restatement § 433A(2).

The Court held that if the record contains conflicting evidence on whether or not apportionment can be made, a question of fact is presented which the fact-finder must resolve under proper instruction including the charge that if the jury is unable to apportion between pre-existing and accident-caused conditions, then the defendant is liable for the entire disability. Other jurisdictions in accord with Bigley include: Matsumoto v. Kaku, 52 Haw. 629, 484 P.2d 147 (1971); Bushong v. Kamiah Grain, Inc., 96 Idaho 659, 534 P.2d 1099 (1975); and McNabb v. Green Real Estate Co., 62 Mich. App. 500, 233 N.W.2d 811 (1975). We note that Bigley is distinguishable from the case before us for several reasons, including the fact that in Bigley liability was established since the jury returned a verdict for $9,100.00.