
USCA1 Opinion

	




                            United States Court of Appeals                            United States Court of Appeals                                For the First Circuit                                For the First Circuit                                 ____________________        No. 94-1258                           WILLIAM AND RITA ESPEAIGNNETTE,                               Plaintiffs, Appellants,                                          v.                             GENE TIERNEY COMPANY, INC.,                                 Defendant, Appellee.                                 ____________________                     APPEAL FROM THE UNITED STATES DISTRICT COURT                              FOR THE DISTRICT OF MAINE                     [Hon. Morton A. Brody, U.S. District Judge]                                            ___________________                                 ____________________                                        Before                                 Selya, Circuit Judge,                                        _____________                            Coffin, Senior Circuit Judge,                                    ____________________                              and Stahl, Circuit Judge.                                         _____________                                 ____________________            Brian  L. Lincicome with  whom Cozen  and O'Connor,  Ted Susi, and            ___________________            ___________________   ________        Laney and Susi were on brief for appellants.        ______________            Roy E.  Thompson, Jr. with whom  Elizabeth G. Knox  and Thompson &            _____________________            _________________      __________        Bowie were on brief for appellee.        _____                                 ____________________                                  December 28, 1994                                 ____________________                      STAHL,   Circuit   Judge.     Plaintiffs-appellants                      STAHL,   Circuit   Judge.                               _______________            William  and Rita Espeaignnette  brought this  action seeking            damages for  the loss of William  Espeaignnette's lower right            arm in  an accident involving a lumber-mill  saw designed and            manufactured  by defendant-appellee Gene  Tierney, Inc. ("the            Company").   Following a four-day  trial, a  jury returned  a            special verdict in favor of the Company, specifically finding            that the  saw  was not  defectively designed.   The  district            court  entered  judgment  for  the  Company and  subsequently            denied   the   Espeaignnettes'  post-trial   motions.     The            Espeaignnettes now appeal, assigning  error to several of the            district court's  evidentiary rulings.  Because  we hold that            the  district  court  abused   its  discretion  in  excluding            evidence pertaining  to subsequent modifications made  to the            saw by Espeaignnette's1 employer,  we vacate the judgment and            remand for new trial.                                          I.                                          I.                                          __                                      Background                                      Background                                      __________                      In  1990,  Espeaignnette's  employer, the  Isaacson            Lumber Company  ("Isaacson"), purchased  a Bottom  Arbor Gang            Saw, or  "edger," designed  and manufactured by  the Company.            Isaacson employs the edger to "square" or "edge" slabs of raw            lumber.   The edger operates in the following manner:  First,                                            ____________________            1.  All references  in the opinion  to "Espeaignnette"  refer            solely to William Espeaignnette.                                         -2-                                          2            the operator feeds slabs of raw lumber into the edger along a            roller table,  passing  the slabs  through anti-kick  fingers            that prevent the slabs from kicking back towards the operator            as  they contact the saw  blades.  After  passing through the            anti-kick fingers, powered infeed  rollers grab the slabs and            pull them into the saw blades.  As designed and manufactured,            the  area surrounding  the anti-kick  fingers and  the infeed            rollers is open and not guarded by any physical covering.                      The operator  controls  the edger  from  a  station            located  at one end of the machine.  During normal operation,            there is no need for the  operator to approach the open space            near the anti-kick fingers and  the infeed rollers, except to            inspect   or  listen   for  strips   of  "edged"   wood  that            occasionally "hang  up" in the  saw-blade area.   When strips            become stuck in this area, the operator must stop the machine            and clear the work surface or risk damaging the saw blades.                      Following    installation     of    the    machine,            Espeaignnette  was   trained  to   operate   the  edger   and            subsequently ran it without  incident for a period of  two to            three  weeks.  According  to his trial  testimony, on October            11, 1990, at approximately  10:30 p.m., Espeaignnette heard a            noise that he  thought indicated  that a sliver  of wood  had            become stuck in the saw-blade section of the edger.   At this            point, Espeaignnette had been working for sixteen hours, with            only a  half-hour lunch break.   Espeaignnette testified that                                         -3-                                          3            he walked to the side of the edger, crouched down, and peered            into the  blades  to investigate.   Espeaignnette  maintained            that  he did not stop the edger while investigating the noise            because  to  do   so  would  needlessly   increase  downtime,            explaining that the edger  often emitted similar sounds that,            upon investigation, did not require a shutdown.                      Espeaignnette  testified that while he was crouched            beside the  edger, he saw a sliver of wood work free from the            saw-blade area.  He then attempted to stand up but, as he did            so,  lost his  balance and  stumbled towards  the edger.   He            further testified that,  as he stumbled, he reached  out with            his right hand to balance himself and inadvertently stuck his            hand into the area  of the infeed rollers, causing  his right            glove to become caught on a roller.  As a result, his arm was            crushed,  pulled into  the saw-blade  area, and  then severed            below the right elbow.2                      Following  the accident, Isaacson  continued to use            the  edger  to cut  raw  lumber.    In the  summer  of  1993,            approximately six months before  trial, an Isaacson  employee            modified  the edger  by  welding to  it  a steel  plate  that            covered the open area by the infeed rollers and the anti-kick            fingers.                                             ____________________            2.  The Company maintains that the accident  occurred because            Espeaignnette  purposely, and  not  inadvertently, stuck  his            hand into the area of  the infeed rollers to free a  piece of            wood.                                         -4-                                          4                      Espeaignnette tried this action against the Company            solely on  a theory  of strict liability,  alleging that  the            edger  was defectively  designed  and unreasonably  dangerous            because of  the lack of physical guards  covering the infeed-            roller  area.    As co-plaintiff,  Rita  Espeaignnette sought            compensation  for  loss  of   consortium  stemming  from  the            injuries to her husband.                      Prior  to trial,  the  Company moved  in limine  to                                                            __ ______            exclude all evidence pertaining to Isaacson's modification of            the edger, and the  Espeaignnettes similarly moved to exclude            evidence  about the absence of comparable accidents involving            edgers  designed   by  the  Company.     The  district  court            provisionally granted  the Company's motion and  excluded the            modification  evidence pursuant  to Fed.  R. Evid.  407 as  a            subsequent  remedial   measure,  subject,  however,   to  the            condition  that  the  Company  not controvert  at  trial  the            feasibility   of   such   a   modification.3      The   court                                            ____________________            3.  Fed. R. Evid. 407 provides:                      When,  after an event, measures are taken                      which,  if  taken previously,  would have                      made  the  event  less  likely  to occur,                      evidence  of  the subsequent  measures is                      not  admissible  to  prove negligence  or                      culpable conduct in  connection with  the                      event.   This  rule does not  require the                      exclusion   of  evidence   of  subsequent                      measures   when   offered   for   another                      purpose,   such  as   proving  ownership,                      control, or  feasibility of precautionary                      measures,     if     controverted,     or                      impeachment.                                         -5-                                          5            provisionally  denied  the Espeaignnettes'  motion  and, over            objection, permitted the owner  of the Company, Gene Tierney,            to testify  about the absence  of reports of  other accidents            involving similar edgers designed by the Company.                        During  trial, the  Espeaignnettes raised  at least            twice the issue of the subsequent-modification evidence.  The            district  court  declined  to  admit  the  evidence  on  each            occurrence.   Although eventually  finding that the  issue of            feasibility  had  been  clearly  raised,  the district  court            nonetheless excluded  the evidence pursuant to  Fed. R. Evid.            403 because the prejudicial impact of the evidence outweighed            its probative  value.4  The  Espeaignnettes made an  offer of            proof  stating,  inter alia,  that  they sought  to  call the                             _____ ____            current operator of the edger to testify that he had operated            the edger  both before and  after its  1993 modification  and            that  the modification had in  no way inhibited the operation            of the machine.                      During  trial, the  district court also  denied the            Espeaignnettes' objections  to the qualification of a witness                                            ____________________            4.  Fed. R. Evid. 403 provides:                      Although   relevant,   evidence  may   be                      excluded  if  its   probative  value   is                      substantially outweighed by the danger of                      unfair   prejudice,   confusion  of   the                      issues,  or  misleading the  jury,  or by                      considerations of undue  delay, waste  of                      time,   or   needless   presentation   of                      cumulative evidence.                                         -6-                                          6            for the Company  as an expert  in "industrial human  factors"            and  to that  witness's testimony  concerning whether  it was            possible for Espeaignnette  to have fallen into  the edger as            he alleged.                      Following  closing  arguments,  the district  court            submitted the case to the jury  as a series of questions on a            special-verdict  form.   The first  question was  whether the            edger  was  "in   a  defective  condition  and   unreasonably            dangerous."   The jury answered this question in the negative            and,  in accordance with the instructions on the form and the            district court's  oral  instructions, proceeded  no  further.            The jury did not answer the subsequent questions on proximate            cause  and assumption  of risk.   Subsequently,  the district            court  entered  judgment  for  the  Company  and  denied  the            Espeaignnettes' motions for judgment as a matter of law and a            new trial.  This appeal followed.                                         II.                                         II.                                         ___                                      Discussion                                      Discussion                                      __________                      The   Espeaignnettes   assign   error    to   three            evidentiary rulings.   They  contend that the  district court            erred  in (1)  excluding under  Rule 403  evidence concerning            Isaacson's  installation  of the  fixed  metal  guard on  the            edger, (2) admitting evidence concerning the absence of other            accidents involving  similar edgers designed  by the Company,            and (3) qualifying a witness for  the Company as an expert in                                         -7-                                          7            "industrial  human  factors" and  permitting  the  witness to            testify on that subject.  We discuss each argument in turn.            A.  Subsequent Modification of the Edger            ________________________________________                      We  begin  by  noting  that a  district  court  has            considerable  latitude  in  determining whether  to  admit or            exclude evidence  under Rule 403.   See, e.g.,  Newell Puerto                                                ___  ____   _____________            Rico,  Ltd. v.  Rubbermaid, Inc.,  20 F.3d  15, 21  (1st Cir.            ___________     ________________            1994).   We  review  these  rulings  only  for  an  abuse  of            discretion.  Daigle v. Maine Medical Ctr., Inc., 14 F.3d 684,                         ______    ________________________            690 (1st Cir. 1994).  "`Only rarely -- and in extraordinarily            compelling circumstances -- will we, from the vista of a cold            appellate  record,  reverse  a district  court's  on-the-spot            judgment concerning the relative  weighing of probative value            and unfair effect.'"   Id. (quoting Freeman  v. Package Mach.                                   ___          _______     _____________            Co., 865 F.2d 1331, 1340 (1st Cir. 1988)).              ___                      Our  review, however,  is  not  completely  without            bite.  See, e.g., Kassel v. Gannett Co., 875 F.2d 935, 951-52                   ___  ____  ______    ___________            (1st Cir. 1989).  In general, "[a]buse occurs when a material            factor  deserving significant  weight  is  ignored,  when  an            improper factor is  relied upon,  or when all  proper and  no            improper factors are assessed, but  the court makes a serious            mistake in  weighing them."  Independent Oil  & Chem. Workers                                         ________________________________            of  Quincy, Inc. v. Procter &  Gamble Mfg. Co., 864 F.2d 927,            ________________    __________________________            929 (1st Cir. 1988).                                         -8-                                          8                      The  Espeaignnettes argue  that the  district court            abused  its  discretion in  excluding  pursuant  to Rule  403            evidence  regarding  Isaacson's  modification of  the  edger.            Primarily, they contend  that the district  court incorrectly            found  that the  danger  of unfair  prejudice outweighed  the            probative value  of the  evidence.  The  Espeaignnettes argue            that the evidence was vital to establishing their prima facie            case  of  strict  liability  under  Maine  law and  that  the            district court  vastly  overestimated the  danger  of  unfair            prejudice.  After a careful review of both the applicable law            and  the facts  and circumstances  surrounding this  case, we            agree.5                      The  Espeaignnettes tried  their claim  against the            Company  pursuant   solely   to  Maine's   strict   liability            statute.6   Under the Maine  statute, a plaintiff  must prove                                            ____________________            5.  Because the district court excluded the evidence at trial            pursuant  to Rule  403,  its pre-trial  ruling excluding  the            evidence under Rule 407 as  a subsequent remedial measure  is            not  at issue.   Nevertheless, because  we are  remanding the            case  for retrial,  we  note that  circuit precedent  clearly            establishes  that Rule 407 does not apply to actions taken by            third parties such  as Isaacson.   Raymond v. Raymond  Corp.,                                               _______    ______________            938 F.2d 1518, 1524 (1st Cir. 1991).              6.  The Maine strict liability statute provides:                      One who sells any  goods or products in a                      defective      condition     unreasonably                      dangerous to the  user or consumer or  to                      his property is subject to  liability for                      physical  harm thereby caused to a person                      whom the manufacturer, seller or supplier                      might  reasonably  have expected  to use,                      consume or  be affected by the  goods, or                                         -9-                                          9            that "the product  was defectively designed thereby  exposing            the  user to  an  unreasonable risk  of  harm."   Stanley  v.                                                              _______            Schiavi Mobile Homes,  Inc., 462 A.2d 1144,  1148 (Me. 1983).            ___________________________            See  also St. Germain v. Husqvarna Corp., 544 A.2d 1283, 1285            ___  ____ ___________    _______________            (Me. 1988).   To determine whether a  product was defectively            designed, Maine courts apply  the "danger-utility" test.  St.                                                                      ___            Germain,  544  A.2d  at 1285.    Under  this  test, proof  of            _______            defective design  includes "an examination of  the utility of            [the  product's]  design,  the risk  of  the  design  and the            feasibility of  safer alternatives."7   Stanley, 462  A.2d at                                                    _______                                            ____________________                      to his property, if the seller is engaged                      in the business of selling such a product                      and it is expected  to and does reach the                      user  or   consumer  without  significant                      change  in the condition  in which  it is                      sold.  This  section applies although the                      seller has exercised all possible care in                      the preparation and  sale of his  product                      and the user  or consumer has  not bought                      the  product  from  or  entered  into any                      contractual relation with the seller.            Me. Rev. Stat. Ann. tit. 14,   221.            7.  In describing the feasibility prong of the danger-utility            test, a leading authority explains that:                      [a]n  alternative  design  that  was  not                      utilized is to be considered  as feasible                      when a reasonable  person would  conclude                      that the (1)  magnitude of the danger-in-                      fact that could have been avoided by such                      alternative design in the (2) utilization                      of the  scientific technological know-how                      reasonably  available  to  the  defendant                      outweighed  the  (1)  financial costs  of                      guarding  against such  avoidable danger,                      (2)  the impairment of  the benefits, and                           _______________________________                      (3)  any  new  danger-in-fact that  would                                         -10-                                          10            1148.   See also Walker  v. General Elec. Co.,  968 F.2d 116,                    ___ ____ ______     _________________            119 (1st Cir. 1992).                        In this case, the excluded evidence of the Isaacson            modification tends  to show that the  design and installation            of a  physical guard was  both possible and  practical (i.e.,            placing a physical guard over the opening did not inhibit the            operation  of  the edger).    Moreover,  this evidence  bears            directly on whether the edger  was defectively designed.   It            allows the jury to compare the utility and  risk of the edger            as actually designed (without the guard) with the utility and            risk  of the alternate  design (with the  guard).  Therefore,            because the evidence was crucial to the Espeaignnettes' case,            unless   the   danger  of   unfair   prejudice  substantially            outweighed its probative value,  the evidence should not have            been excluded.  See Swajian v. General Motors Corp., 916 F.2d                            ___ _______    ____________________            31, 34-35 (1st Cir. 1990) (reversing exclusion under Rule 403            in products liability action  where evidence bore directly on            event in issue); Laney v. Celotex Corp., 901 F.2d 1319, 1320-                             _____    _____________            21 (6th Cir. 1990) (reversing exclusion  under Rule 403 where                                            ____________________                      have  been  created  by  the  alternative                      design.            W. Page Keeton et al., Prosser and Keeton on the Law of Torts                                   ______________________________________              99  at 700  (5th ed.  1984) (emphasis supplied).   Cf.  St.                                                                 ___  ___            Germain,  544  A.2d at  1285-86  (evidence  "that the  safety            _______            feature would minimally impair the  use of the saw" supported            determination   that  evidence  was   sufficient  to  find  a            defective condition  and that, consequently, the  trial court            had  erred in  directing verdict  for manufacturer  on strict            liability claim).                                         -11-                                          11            evidence "[went]  to the fundamental question  of the case").            Cf.  Joseph W. Cotchett & Arnold B. Elkind, Federal Courtroom            ___                                         _________________            Evidence  93 (3d ed. 1993)  ("If the party's  case turns upon            ________            the  introduction  of the  evidence,  [Rule  403] favors  the            admission of the evidence.").                      The   fact    that   the   court    permitted   the            Espeaignnettes'  expert  to  testify to  the  possibility  of            placing a physical guard  on the edger does not  diminish the            probative value  of the excluded  evidence.  The  Company did            not dispute the  fact that it  would have been  theoretically            possible to have installed a physical guard on the edger, but            it  did vigorously  dispute  whether such  a  guard would  be            practical.   The designer of the edger, Gene Tierney, and the            Company's expert witness, Professor Barnett, testified that a            physical guard  would unduly inhibit the  normal operation of            the edger.8   The  excluded evidence  tends to show  directly                                            ____________________            8.  Answering  why he chose  not to include  a physical guard            over  the  open area  of  the edger  where  Espeaignnette was            injured, Tierney testified:                      Utility of the  machine.   I have  found,                      almost without exception, that  where you                      have  a guard  bolted on,  hinged, pinned                      on,  even  clipped, they'll  take  it off                      first time  and it  stays off.   Then you                      have that whole opening exposed.                      Q.   You didn't  put a guard  because you                      were afraid someone would take it off?                      A.   I'm  saying you  use the  utility of                      that machine, how long do  you anticipate                      it  would  take  to take  the  guard  off                                         -12-                                          12                                            ____________________                      assuming  they  did put  it  back?   What                      would that --                      Q.  I'm sorry.  Go ahead.                      A.  What would that do to operator stress                      when  his material  is piling up  on him.                      That's going to make  him fight it, so to                      speak, to  catch up.  He's  more prone to                      error under those  conditions.  All those                      factors are considered.            Professor Barnett testified:                      The  methodology  of trying  to  get that                      thing unjammed is simply horrific, and we                      need every aperture available to us.                           . . .                            Put  those guards  on  the side,  if                           ____________________________________                      they're permanently fixed  on there,  you                      _________________________________________                      have   now   seriously  compromised   the                      _________________________________________                      unjamming capability of  the machine.  If                      ____________________________________                      you  don't put them  on permanently, then                      the task  will be we have  to remove them                      so  we  can  get  in  there  and  do  the                      unjamming  on the  side.   If  you remove                      them, then  the machine is right  back to                      the one we're looking  at in the front of                      the room.            (Emphasis supplied).   In his opening  remarks, the Company's            counsel stated:                           One of the  reasons, you will learn,                      that there  is an  opening  in this  very                      area  is  it is  mandatory that  there be                                _______________________________                      access    to    do    just   what    [the                      ______                      Espeaignnettes'  counsel] indicated,  and                      that is unjam, unplug  what can happen in                      there.   There is a necessity  to look in                      that  area and  to, once  the machine  is                      turned off, reach in and unplug it.            (Emphasis  supplied).    In addition,  the  Company's counsel            argued at closing:                      This machine  had to be  designed to keep                      this downtime to a minimum.                                         -13-                                          13            that a physical guard  does not inhibit the operation  of the            edger  and therefore  would  have rebutted  the testimony  of            Tierney  and Professor  Barnett  much more  effectively  than            hypothetical   assertions   by  the   Espeaignnettes'  expert            witness.                      Not only  did the district court  incorrectly gauge            the probative  value of the testimony,  it also overestimated            the  danger of unfair prejudice.  It is, of course, axiomatic            that "[a]ll  evidence is  meant to be  prejudicial; elsewise,            the proponent would  be unlikely  to offer it."   Daigle,  14                                                              ______            F.3d at  690.    The  appropriate  inquiry  under  Rule  403,            therefore,  is   whether  the  evidence  results  in  "unfair            prejudice."    See  Swajian,  916  F.2d  at  34.     "`Unfair                           ___  _______                                            ____________________                           . . .                           And I  want you to think  just for a                      moment about some  testimony relative  to                      the jams  when the slab goes  in and gets                      really   hung   up   in  those   rollers.                      (Gesturing)  To get that slab out, you're                      going to have to go into the area between                      the  in-feed  rollers  and  the  kickback                      fingers.                           If you open up the machine and go in                      this way,  you're only getting one end of                      it.   You're not  getting the  major jam,                      which is where -- the in-feed rollers and                      the  antikickback fingers.    You had  to                                                    ___________                      have access in that area.                      ________________________            (Emphasis supplied).   Cf. Borden, Inc. v. Florida East Coast                                   ___ ____________    __________________            Ry. Co., 772 F.2d 750, 756 (11th Cir. 1985) ("[A] litigant is            _______            unduly   prejudiced  when  his   opponent  is  successful  in            preventing  the  admission  of  evidence  on  a  particularly            crucial issue in dispute,  and then points to the  absence of            such evidence in closing argument.")                                         -14-                                          14            prejudice'  . . . means an undue tendency to suggest decision            on an  improper basis,  commonly, though not  necessarily, an            emotional one."  Fed R.  Evid. 403 advisory committee's note.                      In  its final  trial  ruling,  the  district  court            excluded the evidence, reasoning only that:                       the prejudicial impact  of that  evidence                      as it relates  to Isaacson correcting the                      machine or having the  machine corrected,                      the prejudicial impact  of that  evidence                      outweighs  the  probative  value   of  it                      because the jury may very well infer from                      that activity  that that was  -- they may                      take   that   evidence  as   evidence  of                      negligence  or  product liability  on the                      part   of   the  defendant   rather  than                      evidence  for  which   it  is   intended;                      namely, the feasibility of   putting that                      or making that repair on the machine.                      The  district   court   viewed  the   evidence   as            admissible  (if at  all)  only to  show feasibility  under an            exception  to   Rule  407.     Therefore,  in   weighing  the            prejudicial  impact  of  the  evidence,  the  court  examined            whether  it  would  tend to  show  something  more  than just            feasibility  (e.g. negligence  or  product  liability).    As            noted, however, because  a third party, and not  the Company,            modified the edger, the evidence  of the modification was not            subject  to  exclusion under  Rule 407.    See supra  note 5.                                                       ___ _____            Therefore,  the  fact  that  the   Espeaignnettes'  proffered            evidence  may  have tended  to  show  "negligence or  product            liability" rather  than just feasibility did  not, by itself,                                         -15-                                          15            constitute an improper  use of the  evidence and warrant  its            exclusion as unfairly prejudicial under Rule 403.                        Moreover,  once the  analysis is  conducted outside            the Rule 407 framework,  we do not believe that  the excluded            evidence posed any significant risk of unfair prejudice.  The            Isaacson modification  was not a subsequent  design developed            well after the  edger was  manufactured.  Hence,  it was  not            (arguably) misleading or unfairly prejudicial on the issue of            whether the edger was  unreasonably dangerous at the time  of            manufacture.    See,  e.g.,  Grenada Steel  Indus.,  Inc.  v.                            ___   ____   ____________________________            Alabama Oxygen Co., 695 F.2d 883, 889 (5th Cir. 1983) (design            __________________            changes  developed after  the manufacture  of the  product in                     _________            question are  irrelevant to the reasonableness  of the design            at  the time of manufacture).  True, Isaacson did not install            a  guard on  the edger until  more than  two years  after the            accident.   The  Company, however,  does not  contend  that a            guard  could  not  have  been   installed  at  the  time   of            manufacture or even that the installation was not considered.            Therefore, the Espeaignnettes'  proffered evidence would  not            have introduced design  choices not known or feasible  at the            time of manufacture.                      Furthermore, the Company's failure in  its brief to            illustrate how  the  excluded evidence  would  be  "unfairly"            prejudicial to its case confirms our conclusion.  The Company            argues only that  the testimony would have been confusing and                                         -16-                                          16            misleading  to  the  jury  because  the  guard  installed  by            Isaacson  was a different  type of guard  (a permanent guard)            than the  guard recommended by the  Espeaignnettes' expert (a            removable guard).  Though this is a difference, we cannot say            that it is particularly confusing or unfairly prejudicial.                      In sum, the proffered evidence posed no significant            risk of unfair prejudice.9                      Nevertheless, we remain mindful of  the substantial            deference  that is  properly accorded  to a  district court's            judgment in "`steadying the  Rule 403 seesaw.'"   Kassel, 875                                                              ______            F.2d at 952 (quoting Onujiogu, 817  F.2d at 6).  The question                                 ________            is not whether we would strike the balance differently in the            first instance, but whether the balance actually struck is so            egregiously  one-sided  that  it   requires  reversal.    Our            decision in Swajian v. General Motors Corp., 916 F.2d 31 (1st                        _______    ____________________            Cir. 1990), in  which we reversed a district court's decision                                            ____________________            9.  We also note that in its provisional ruling before trial,            the  district court excluded the evidence under Rule 407, but            added, "I am more concerned, frankly, with prejudicial impact            that  that  kind   of  evidence  would  have   on  the  jury;            specifically, that  portion of  the evidence  which indicates            that  the  same  machine, at  the  same  place,  in the  same            factory,  was in  fact  remedied  to  prevent  this  kind  of            accident."    The  district  court  did  not  reiterate  this            reasoning when it excluded  the evidence under Rule 403.   In            any event, we are unconvinced that the fact that the evidence            concerned the specific edger  involved in the accident evokes            any special degree of unfair prejudice in this case.                                  ______                                         -17-                                          17            in a  products liability action to  exclude evidence pursuant            to Rule 403, informs our analysis on this issue.10                        In Swajian, the plaintiff's  wife was killed when a                         _______            truck she  had been driving rolled over  in an accident.  The            plaintiff contended that the  truck's rear axle was defective            and had caused the accident.  General Motors argued, however,            that driver error was the cause.  The district court excluded            evidence  that the decedent  had been  drinking prior  to the            accident, finding that the evidence was "unduly inflammatory"            and  that  its  prejudicial  impact would  far  outweigh  its            probative value.  Id. at 34.                                ___                      On  appeal, we  reversed, criticizing  the district            court for its  failure in  striking the Rule  403 balance  to            distinguish between evidence that is prejudicial and evidence            that  is  unfairly prejudicial.   Id.  at  35.   Moreover, we                      ________                ___            stressed that  the evidence  was highly probative  because it            bore directly on the issue of causation.  Id.                                                      ___                      As  in  Swajian, the  evidence  excluded here  bore                              _______            directly  on an  essential element  of the  plaintiff's prima                                            ____________________            10.  Even though  Swajian suggests that, there,  the district                              _______            court  erred as  a  matter of  law by  not making  a specific            finding   of  "unfair   prejudice,"  the   opinion  is   best            interpreted  as holding  that the  district court  abused its            discretion  in  conducting   the  balancing  that  Rule   403            requires.   This  can  be deduced  from  the Swajian  panel's                                                         _______            review of  the district court's balancing  of probative value            against prejudicial  impact, Swajian, 916 F.2d  at 34, which,                                         _______            in turn, supports a conclusion that the district court abused            its discretion in striking the balance in this case.                                         -18-                                          18            facie case.  Furthermore, as compared to the circumstances of            this  case, we  think that  the risk  of unfair  prejudice in            Swajian was  decidedly more pronounced.   In Swajian,  a real            _______                                      _______            danger undoubtedly existed that the jury would have taken the            evidence of the  decedent's drinking as showing  that she was            at  fault and  not  entitled to  compensation, regardless  of            whether  or not  the axle  failure caused  the accident.   In            contrast, as  we have explained above,  the evidence excluded            in this case posed little, if any, risk of unfair prejudice.                                                       ______                      In sum, we are convinced that the excluded evidence            was  highly probative on an essential disputed element in the            case and  that the danger  of unfair prejudice  was extremely            remote.  Accordingly, we hold that the district court  abused            its discretion in excluding the proffered evidence.11                      Our  determination that  the district  court abused            its discretion  in striking  the Rule  403 balance does  not,            however, end our analysis.  As with most trial errors, we are            not  empowered   to  notice  error  in   a  district  court's            evidentiary ruling  "unless a substantial right  of the party                                            ____________________            11.  We  further note  that the  cases on  which  the Company            relies  to   support  excluding  the   evidence  are  clearly            distinguishable.  See Harrison v.  Sears, Roebuck & Co.,  981                              ___ ________     ____________________            F.2d 25,  31-32 (1st  Cir.  1992) (negligence  and breach  of            warranty action, evidence offered to  impeach only); Raymond,                                                                 _______            938  F.2d  at  1523-24  (feasibility  stipulated  and  design            modification developed after manufacture of product); Grenada                                                                  _______            Steel, 695 F.2d at  888-89 (feasibility clearly not contested            _____            and  design  changes  developed  years  after  manufacture of            product).                                         -19-                                          19            is affected."  Fed. R. Evid. 103(a); see also Fed. R. Civ. P.                                                 ___ ____            61.   In  determining whether  an  error affected  a  party's            substantial right,  "[t]he central question  is whether  this            court can say with fair assurance . . . that the judgment was            not substantially swayed  by the error."   Lubanski v. Coleco                                                       ________    ______            Indus.,  Inc., 929  F.2d  42, 46  (1st  Cir. 1991)  (internal            _____________            quotations omitted).                       The exclusion of the proffered  testimony cannot be            considered  harmless.    As  noted,  the   evidence  directly            pertains to  whether the edger was  unreasonably dangerous at            the time of manufacture.   Therefore, we cannot say  that its            absence did  not substantially affect the  jury's decision on            this point.                      Furthermore, the only issue the jury considered was            whether the edger was unreasonably dangerous.  In accord with            the court's instructions, the  jury returned a single finding            that  the  edger  was  not  "in  a  defective  condition  and            unreasonably  dangerous."    The  jury  did  not  answer  the            subsequent questions on  the special-verdict form  concerning            proximate cause and assumption of risk.  As a result, because            the  exclusion of  the  evidence undermined  the jury's  sole            finding that the edger  was not in a defective  condition, it            therefore affected a substantial right of the Espeaignnettes.            B.  Absence of other accidents            ______________________________                                         -20-                                          20                      The  Espeaignnettes contend that the district court            erred in  admitting evidence  concerning the lack  of similar            accidents  involving edgers  designed  by the  Company.   The            Espeaignnettes argue  that this  evidence is irrelevant  in a            strict  liability action  and, in  the alternative,  that the            Company  failed  to establish  a  proper  foundation for  the            evidence.  The Espeaignnettes fail on both grounds.                      As  an initial  matter, we  note that  both parties            argued this  issue before  the district  court  and in  their            briefs  as though it were  controlled by state  law.  Neither            side  discussed the  applicability  of the  Federal Rules  of            Evidence.  Nevertheless, it  is axiomatic that in determining            whether evidence  is relevant, and therefore  admissible in a                                 ________            diversity action,  the Federal  Rules of Evidence  supply the            appropriate rules of decision.  See, e.g., McInnis v. A.M.F.,                                            ___  ____  _______    _______            Inc., 765 F.2d  240, 245-46  (1st Cir. 1985);  Fed. R.  Evid.            ____            1101.   Normally,  the Espeaignnettes'  failure to  argue the            correct  applicable standard  would  effect a  waiver of  the            issue.    Because we  are  remanding the  issue  for retrial,            however,  we will proceed to  discuss the issue  as it arises            under the Federal Rules of Evidence.                        Subject  to  certain limitations,  all  evidence is            admissible if it is relevant -- i.e., if it tends to make the            existence or  nonexistence of a disputed  fact "more probable            than it would  be without the evidence."  Fed.  R. Evid. 401,                                         -21-                                          21            402.   As  we have  discussed earlier,  a district  court may            nonetheless exclude relevant evidence if the  probative value            of the evidence is "substantially outweighed by the danger of            unfair prejudice, confusion of  the issues, or misleading the            jury,  or by considerations of undue delay, waste of time, or            needless presentation of cumulative evidence."  Fed. R. Evid.            403.                      In general, courts have recognized that the absence            of prior accidents may be admissible to show:                      (1)   absence  of  the  defect  or  other                      condition alleged,                      (2) the  lack  of a  causal  relationship                      between  the injury  and  the  defect  or                      condition charged, [and]                      (3)   the   nonexistence  of   an  unduly                      dangerous situation.            Strong, 1 McCormick on  Evidence   200 at 850-51.   Moreover,                      ______________________            we  recently rejected the argument that  evidence of the lack            of prior accidents is irrelevant on the issue of causation in            a  products liability  case brought  on a  negligence theory.            Harrison v. Sears,  Roebuck & Co., 981 F.2d  25, 30 (1st Cir.            ________    _____________________            1992).  See also  Keller v. United States, No.  94-1136, slip                    ___ ____  ______    _____________            op.  at 27, 30  (1st Cir. Oct. 19,  1994) (noting evidence of            the absence of other accidents as supporting district court's            failure  to find  design  defect or  causation in  negligence            case).12                                             ____________________            12.  The  Espeaignnettes argue,  however,  that  even if  the            absence  of prior accidents would be relevant in a negligence            case,  the  district court  should  still  have excluded  the                                         -22-                                          22                      The evidence  of the absence of  prior accidents is            clearly  relevant to  several disputed  issues in  this case.            The  fact that the Company had received no reports of similar            accidents tends to  disprove causation.   That there were  no            similar reports  of injuries due to  inadvertent contact with            the infeed rollers tends  to support the Company's contention            that  it was not possible  for Espeaignnette to have stumbled            accidentally into the open  area of the edger as  he alleged.            Additionally, the absence of prior accidents is probative and            relevant to  whether the  edger as designed  was unreasonably            dangerous.                      The Espeaignnettes alternatively  contend that  the            Company  failed to  establish  the  necessary foundation  for            admission  of the evidence.   A review of  the cases reveals,            for  the most  part, that  evidence of  the absence  of prior            accidents may not be admitted unless the offering party first            establishes that  the  "lack of  accidents was  in regard  to            products that are substantially identical to the one at issue            and used in settings  and circumstances sufficiently  similar            to   those  surrounding  the  machine  at  the  time  of  the                                            ____________________            evidence because the issue here turns solely on principles of            strict liability.   This  argument is not  persuasive because            the  Maine  Supreme   Judicial  Court  has  recognized   that            negligence and  strict liability causes of  action both share            the same elements  of causation  and defective  design.   See                                                                      ___            Marois  v. Paper Converting Mach. Co., 539 A.2d 621, 623 (Me.            ______     __________________________            1988) (causation)  and Stanley,  462 A.2d at  1148 (defective                               ___ _______            design).                                             -23-                                          23            accident."    Klonowski v.  International Armament  Corp., 17                          _________     _____________________________            F.3d 992, 996 (7th  Cir. 1994) (internal quotations omitted).            Whether such preliminary requirements are aimed at preventing            the  admission  of   irrelevant  evidence  under   Rule  402,            excluding relevant  evidence that is unfairly prejudicial and            confusing under Rule 403, or both, is unclear.  Cf.  Fusco v.                                                            ___  _____            General Motors  Corp.,  11  F.3d 259,  264  (1st  Cir.  1993)            _____________________            (foundational requirement of substantial similarity regarding            evidence of  similar accidents "now loosely  appended to Rule            403").   In  any  event, the  determination of  admissibility            turns  on the  facts and  circumstances of  each case  and is            committed, in the first instance,  to the sound discretion of            the  district judge.  See  United States v.  Brandon, 17 F.3d                                  ___  _____________     _______            409, 444 (1st  Cir.), cert. denied, 115 S. Ct.  80, and cert.                                  _____ ______                  ___ _____            denied, 115 S. Ct. 81 (1994); Fed. R. Evid. 104(a).            ______                      Prior  to  testifying  about  the  lack of  similar            accidents, Tierney  testified that, since  1976, his  company            had sold eighty-seven edgers  using essentially the same open            infeed-roller design.  He also testified that as president of            the Company any  claims or notices of accidents  involving an            edger  designed and  manufactured by  the Company  would have            come to his  attention.  While  in different circumstances  a            district   court  might  require   more  to  show  sufficient            similarity,  we think  that  Tierney's testimony  established            that  the  evidence of  the  absence of  other  accidents was                                         -24-                                          24            admissible  in  this case.    Furthermore, we  note  that the            Espeaignnettes'  counsel  soundly  attacked   this  testimony            during cross-examination,  bringing out that  Tierney did not            know whether any of the machines had been modified or if they            had been  situated so as  to prevent accidental  contact with            the infeed rollers.             C.  Expert testimony            ____________________                      The Espeaignnettes'  final  complaint is  that  the            district  court  improperly  permitted the  Company's  expert            witness to testify  that it was  not physically possible  for            Espeaignnette  to  stumble and  fall  into  the  edger as  he            contended.  Specifically, the Espeaignnettes contend that the            Company's  expert lacked sufficient qualifications to testify            as an  "industrial human  factors" expert in  machine design.            They further argue that  the subject of the testimony  -- how            one  reacts during a stumble  -- was an  improper subject for            expert testimony because it was  within the knowledge of  the            average juror.  We do not agree.                      Determinations of whether a witness is sufficiently            qualified  to testify  as an  expert on  a given  subject and            whether such expert  testimony would be helpful  to the trier            of  fact are committed to  the sound discretion  of the trial            court.   See, e.g., Navarro  de Cosme v.  Hospital Pavia, 922                     ___  ____  _________________     ______________            F.2d 926, 931 (1st Cir. 1991).  "[A] trial judge's rulings in            this  sphere should be upheld `unless manifestly erroneous.'"                                         -25-                                          25            United  States  v. Sepulveda,  15 F.3d  1161, 1183  (1st Cir.            ______________     _________            1993) (quoting Salem v. United States Lines Co., 370 U.S. 31,                           _____    _______________________            35 (1962)), cert. denied, 114 S. Ct. 2714 (1994); but compare                        _____ ______                          ___ _______            Williams v. Poulos, 11 F.3d 271, 282 (1st Cir. 1993) (stating            ________    ______            standard of review is abuse of discretion).                        A review of Professor  Barnett's vita and testimony            reveals  that,  although  he   has  little  formal  education            regarding "industrial human factors," he  does have extensive            professional experience  in the field.  His testimony was not            restricted to how a  person reacts during a stumble.   Rather            he gave important testimony explaining human interaction with            machines, an issue both important in evaluating the Company's            decision  not  to place  a physical  guard  on the  edger and            relevant to the Company's theory  of causation.  The district            court did  not abuse its  discretion in either  accepting the            qualifications of Professor Barnett as an expert or admitting            his testimony.                                         III.                                         III.                                         ____                                      Conclusion                                      Conclusion                                      __________                      For the  foregoing reasons, we vacate  the judgment            entered  below and remand this case to the district court for            a new trial.                                         -26-                                          26
