December 14, 1993 UNITED STATES COURT OF APPEALS
                    FOR THE FIRST CIRCUIT
                                        

No. 92-2473
No. 93-1801

                      CAROL GAGNE FUSCO,

                     Plaintiff, Appellee,

                              v.

                 GENERAL MOTORS CORPORATION,

                    Defendant, Appellant.

                                         

                         ERRATA SHEET

   The opinion  of this  Court issued on  December 6,  1993, is
amended as follows:

   On page 4, line 1  of first full paragraph, replace "General
Motors'" with "General Motors".

                UNITED STATES COURT OF APPEALS
                    FOR THE FIRST CIRCUIT
                                         

No. 92-2473
No. 93-1801

                      CAROL GAGNE FUSCO,

                     Plaintiff, Appellee,

                              v.

                 GENERAL MOTORS CORPORATION,

                    Defendant, Appellant.

                                         

        APPEALS FROM THE UNITED STATES DISTRICT COURT

              FOR THE DISTRICT OF NEW HAMPSHIRE

    [Hon. Martin F. Loughlin, Senior U.S. District Judge]
                                                        

                                         

                            Before

                    Boudin, Circuit Judge,
                                         

         Coffin and Campbell, Senior Circuit Judges.
                                                   

                                         

Thomas J. Sweeney with whom Howard B. Myers, Terrence E.  Haggerty
                                                                  
and Bowman and Brooke were on brief for appellant.
                 
Robert K.  Mekeel with  whom Law  Offices of  Joseph F.  McDowell,
                                                                  
III, P.A., William  J. Murphy,  Robert T.  Shaffer, III  and Murphy  &amp;
                                                                  
Shaffer were on brief for appellee.
   

                                         
                       December 6, 1993
                                         

     BOUDIN, Circuit Judge.  Carol Fusco was injured in a car
                          

accident and brought  suit against General Motors,  the car's

manufacturer.  A jury awarded Fusco $1 million in damages and

General Motors has appealed, challenging rulings on  evidence

and discovery made by the district judge.  We affirm.

                              I.

     On December  15,  1986, Fusco  was  driving her  car,  a

Chevrolet  Chevette, near  Pelham, New  Hampshire.   Her  car

suddenly  left  the  roadway,  slid   across  an  ice-covered

embankment,  and hit  a telephone  pole  somewhere along  the

front left side of the car.  Fusco was injured.

     Fusco brought suit against General Motors in state court

in  New  Hampshire, claiming  that  a  key component  in  the

steering system--the front left  "ball stud"--had broken from

metal  fatigue  and  caused the  disaster.1    General Motors

removed the  case  to federal  district  court and  took  the

position that  the ball stud  had not been  the cause  of the

accident  but  rather  had fractured  when  the  car hit  the

telephone  pole.   A  jury  trial,  begun  on July  7,  1992,

resulted in  an evenly  divided hung  jury, and  the district

court promptly ordered a second trial for November 16, 1992.

                    

     1It appears that  the ball is a spherical  object with a
protruding stud; that the ball and stud together form part of
the  elaborate connection (via the tie rod and steering gear)
between  the tire wheel or  axle and the  steering wheel.  If
the  stud  breaks  entirely,  the tire  wheel  is  no  longer
controlled by the steering wheel.

                             -2-

     At the  second trial Fusco offered  eyewitness testimony

that her car had abruptly veered off the highway and collided

with a telephone pole.  A state trooper  who arrived first at

the accident testified  that the car was  resting against the

pole near the  hinge pillar on the driver's  side, a location

between the  door and the  left front fender.   Fusco offered

two  experts (Robert Walson  and Carl  Thelin) who,  based in

part on  this testimony and  their examination of  the broken

ball stud, concluded that  metal fatigue had caused  the stud

to break, causing the steering  apparatus to fail and the car

to veer into the pole.

     Walson,  a metallurgist,  testified that the  surface of

the   broken   ball   stud  taken   from   Fusco's   car  was

characteristic of a fatigue, rather than an impact, fracture.

He  supported his  opinion  in  several  ways  including  his

pretrial examination of the surface  of the ball stud under a

scanning electron microscope; he was fiercely  cross-examined

by  General  Motors  about  this  examination.    Thelin,  an

automotive  engineer, testified  that General  Motors' design

and quality control of the  ball stud were inadequate.  Based

on partial reconstruction of the accident, he also challenged

General Motors' argument that the telephone pole impact could

have broken the ball stud.

     General Motors' case included testimony from  its expert

Jerry  Chiddister who reconstructed the accident based on his

                             -3-

experience with many  crash tests.  In his  view, the car had

"sideslipped" into  the telephone  pole, causing  the car  to

slide along  the pole starting  at the front left  fender and

ending with the pole lying next to the door hinge column.  He

opined that on  its travel down the side of the car, the pole

hit the front left tire and the impact broke the ball stud, a

predictable  occurrence given the estimated speed of the car.

Had the  stud broken before  the car veered,  Chiddister said

that there would  have been a  heavy black tire  mark on  the

road  because the uncontrolled tire would have dragged as the

car slid off course.

     Kirk  Ulman,  another General  Motors  expert, testified

that he had examined  the ball stud itself.  He explained why

the  location of the  break (at  the neck  of the  stud), the

surface  of the break (grainy  with chevron marks), and other

characteristics meant  that impact  and not  fatigue was  the

cause.   James Willis, who worked in General Motors' facility

that made the steering gear, testified to quality control and

the  nature of simulated  fatigue fractures.   Ray Schultz, a

metallurgist, confirmed Ulman's testimony on key points.

     The  jury rendered  a  verdict  in  favor of  Fusco  and

awarded  her $1  million  in damages.    General Motors  then

appealed.  In its brief General Motors does not challenge the

sufficiency  of  Fusco's  evidence  but  confines  itself  to

contesting several evidentiary and discovery rulings, rulings

                             -4-

that can  only  be understood  against  the backdrop  of  the

testimony  already described.  Although these claims of error

are not frivolous, we do not think that  any of them warrants

further proceedings.

                             II.

     General  Motors' first  claim  on  appeal  is  that  the

district  court erred in  ruling, prior  to the  first trial,

that two videotapes--the  "driving tapes"--were inadmissible.

The main tape  made in  1992 has  two parts.   In the  indoor

part, Ulman  used a  car mounted  on a  lift  to display  the

function of the  ball stud and tie rod and showed how in this

demonstration  the connection between  the stud and  the tire

wheel or axle had  been altered in the  test vehicle so  that

the stud could be released deliberately from inside the car.

     In the  outdoor part,  filmed at  a General Motors  test

track, Ulman drove the Chevette while Willis,  sitting in the

passenger  seat, intentionally disconnected  the tie rod from

the tire  wheel.  The film  showed that, when  the left wheel

finally  separated from  the rod,  the  wheel flopped  out of

alignment with  the right  wheel and  dragged on  the highway

apparently creating a  long black skid mark.  The car did not

veer out of  control or  hit the  track barrier.   The  other

tape, made  in  1986,  simply  showed a  similar  test  track

demonstration with a  different driver and passenger.   Thus,

                             -5-

there is no need for  an independent discussion of this tape.

     When General Motors produced the tapes to Fusco in  June

1992, shortly before the first  trial, Fusco made a motion in
                                                             

limine  to  exclude   them,  arguing  that  the   test  track
      

conditions did not  duplicate the conditions that  existed at

the time  of the actual accident.  In  an oral ruling on July

8,  1992,  the  trial judge  granted  the  motion.   Although

General Motors argues  that the  exclusion of  the tapes  was

error, it  did not  seek to  offer the  tapes  at the  second

trial.

     Seizing  on  this omission,  Fusco  argues that  General

Motors has waived  its right to argue that  the exclusion was

error.   Fusco  points to  cases  holding that  an in  limine
                                                             

ruling on evidence  may not be reviewed on  appeal unless the

offer  or  objection  is renewed  when  evidence  is actually

presented at trial.   This court has made general  statements

to this  effect, e.g., United States v. Reed, 977 F.2d 14, 17
                                            

(1st  Cir. 1992),  in cases  where  the in  limine motion  to
                                                  

exclude was denied and the opponent of the evidence failed to

renew the objection at trial. We  have found no case in  this

circuit, however,  where an in  limine motion to  exclude was
                                      

granted  and the  proponent  of the  evidence, by  failing to

renew the offer at trial, was found to have waived the issue.

                             -6-

     Where an  objection to  evidence has  been overruled  in
                                                             

limine,  it makes  sense  to require  that  the objection  be
      

renewed at trial.  However  definite the denial of the motion

to  exclude  prior to  trial,  it  is  child's play  for  the

opponent  of the  evidence  to renew  the objection  when the

evidence  is  actually  offered; and  requiring  this renewal

gives the trial judge a  chance to reconsider the ruling with

the concrete  evidence presented in the actual context of the

trial.  The only criticism one might offer of the requirement

is that  the Federal  Rules of Evidence  say nothing  about a

second  objection,2 but any practiced trial lawyer knows that

much of the law of evidence is not contained in these written

rules.

     On  the  other  hand,  where  the  motion  in limine  is
                                                         

granted, and the  proponent of the evidence is  told that the

evidence  will not be  admitted, the situation  is different.

To require that the evidence  be offered again at trial would

certainly give the trial court  a second chance, but doing so

can  hardly be  described  as  easy:   on  the contrary,  the

proponent   would  have  to   engage  in  the   wasteful  and

inconvenient  task  of  summoning   witnesses  or  organizing

                    

     2The Federal Rules of Evidence do  not address in limine
                                                             
motions at all.   Instead the rules require  in general terms
that,  to  preserve a  ruling  on  evidence  for appeal,  the
proponent  of evidence make its  substance known to the court
and an opponent make known  the objection to the evidence and
the ground of the objection.  Fed. R. Evid. 103(a).

                             -7-

demonstrative evidence  that the  proponent has  already been

told not to  offer.  Indeed, in many cases the prior grant of

the  in limine  motion would  make it  improper to  call such
              

witnesses  without prior permission.  All the proponent could

do would be  to line up the  witnesses at trial and  then ask

permission.

     Although a  symmetrical rule  may be  preferable if  all

else is  equal, all else  is not equal  here.  Where  a court

rules in limine  that certain  evidence is  excluded but  the
               

ruling is merely  tentative or qualified, then  the proponent

might well have  to offer the evidence  at trial in order  to

preserve an appeal on the issue.   Fed. R. Evid. 103(a).  But

where  the pretrial  proffer  is  adequate  and  evidence  is

excluded unconditionally by  a pretrial order, then  we think

that the  proponent has  preserved the  issue for appeal  and

(other  circumstances  being unchanged)  need  not  bring the

witness  to court  and proffer  the evidence again  at trial.

See  McQuaig  v.  McCoy, 806  F.2d  1298,  1301-02 (5th  Cir.
                       

1987).3   The result  is the  same here  where the  in limine
                                                             

                    

     3Preserving the  claim of  error based  on exclusion  of
evidence requires  an adequate proffer, so that the trial and
appellate courts  know what  evidence is at  issue.   Fed. R.
Evid. 103(a).   There  may also  be cases  where a  change in
circum-stances,  after the in limine ruling but before trial,
                                    
might make it  unreasonable for the proponent to  rely on the
solely in  limine ruling to  preserve the issue (a  new basis
                 
for admissibility might  arise or the court's  initial reason
for exclusion might be mooted).

                             -8-

order preceded the  first trial because no one  disputes that

the same order governed the second trial.

     Needless  to say, most district judges are very cautious

about making a definitive ruling in limine that evidence will
                                          

not be received at trial.  Trial judges know better than most

that many issues  are best resolved in context  and only when

finally necessary.   But here, as happens from  time to time,

the trial judge did rule definitively that the evidence would

not be  admitted.  The  proffer was adequate since  the tapes

were apparently  available to  the court.   And no  change in

circumstances  occurred after the in limine ruling that might
                                           

have  affected the controlling  ground for exclusion  or cast

any  doubt on  the trial  judge's intention  to abide  by the

original ruling.

     Thus we turn  to the merits of the  ruling excluding the

driving tapes.  The oral ruling was terse ("You don't have to

argue it.   I'm not  going to let  it in.") but  the district

judge had a written motion from Fusco, and a written response

from  General Motors, and made the ruling only after allowing

both  sides  to argue  their  points  orally.   Fusco's  main

objection was that  the taped scene on the test track did not

adequately  replicate the conditions of the accident.  Merely

to state  the obvious, no  one claimed that the  accident had

occurred when a  jury-rigged cotter pin  was pulled from  the

ball stud by a wire leading into the passenger seat.  Another

                             -9-

facially obvious difference  is that the test car  was driven

by an experienced driver who expected the break to occur.  

     General Motors readily admitted that the conditions were

not  the same but argued that the tape was admissible to show

general scientific  principles and  that the  dissimilarities

went  to  weight and  not  admissibility.4   It  repeats this

argument on appeal,  adding that under Fed. R.  Evid. 403 the

burden was  upon Fusco (as  the opponent of the  evidence) to

show that prejudice substantially outweighed probative value.

General Motors says that not only did Fusco fail to show that

the dissimilarities were important but, in addition,  General

Motors'  own experts would have said that the dissimilarities

were not significant.

     The problems raised  by demonstrations of this  kind are

interesting  and important.  The test track replication shown

on the driving tapes (this court was furnished with copies of

the tapes) is vivid and pertinent: one sees, in a way that no

words could capture, the tire wheel flip out of alignment and

the tire then dragging on the  track.  The impression left is

that such an  accident would leave a tire  streak, as claimed

                    

     4General Motors does  not claim that the  indoor portion
of the  tape was admissible independently; and indeed most of
the indoor portion  was merely to lay the  groundwork for the
test.   The indoor portion did  show Ulman using a  straw, in
place of  the stud, to show how the  stud could be bent by an
impact on the  rear portion of the wheel,  but General Motors
does  not claim that this  brief sequence justified the tape,
and  it could  easily have  been replicated  in court  with a
mock-up.

                             -10-

by General Motors, and  that the car  is more likely to  flop

and drag  than to veer  sharply off the  road.  A  lay juror,

asked whether  a look  at the tapes  would be  helpful, would

likely answer yes.

     The  case law  in this  area  is muddled,  as one  might

expect, but the tendency of the court is to  treat this class

of demonstrative evidence more skeptically than would the lay

juror.  The  concern lies not with  use of tape or  film (the

issue would  be largely the same if  the jurors were taken to

the test  track  for  a  live  demonstration)  but  with  the

deliberate recreation  of an event  under staged  conditions.

Where  that  recreation  could easily  seem  to  resemble the

actual occurrence, courts have feared  that the jurors may be

misled because they do not fully appreciate how variations in

the   surrounding   conditions,  as   between   the  original

occurrence and the staged event, can alter the outcome.

     In such  cases the  solution of  many courts,  including

this  one,  has been  to call  for substantial  similarity in

conditions,  or to stress  the great discretion  of the trial

judge to exclude the evidence  where similarity is not shown,

or both.  E.g.. Swajian v.  General Motors, 916 F.2d 31  (1st
                                          

Cir.  1990); see  1 J.  Strong, McCormick  on Evidence    202
                                                      

(1992) (collecting cases,  a number of which  involve General

Motors).   This case  law largely  undercuts General  Motors'

claim that the burden lay with Fusco to show undue prejudice;

                             -11-

instead,  courts have created  a doctrine, predating  and now

loosely  appended to Rule  403, that requires  a foundational

showing of  substantial  similarity in  circumstances.    Cf.
                                                             

Daubert v. Merrell Dow Pharmaceuticals, Inc., 113 S. Ct. 2786
                                            

(1993)  (reliability requirement  for  expert testimony  held

implicit in Rule 702).

     Of course  the concept  of substantial  similarity is  a

flexible  one, and  ought  to  be, for  the  benefits of  the

demonstration and  the dangers  of misleading  the jury  will

vary greatly  depending upon  the facts.   We think  that the

trial judge enjoys  great discretion in this area.   But here

the circumstances  were not similar: as in  Swajian, the test
                                                   

occurred in  controlled conditions,  on a  test track  with a

driver expecting the occurrence, and with a doctored piece of

equipment rather than  one that actually broke.   916 F.2d at

36.   General  Motors does  not  seriously claim  substantial

similarity,  despite  its  reference  to  the  testimony  its

experts would have given.

     Instead,  General Motors says  that the tapes  here were

designed  not  to   recreate  the  accident  but   rather  to

illustrate  general "scientific  principles," presumably  the

behavior of a car with a disconnected ball stud.  Admittedly,

"[w]hen this  [scientific  principles]  label  is  attached,"

courts often do  ask not about  similarity of conditions  but

only whether  the test  was properly  conducted.   McCormick,
                                                            

                             -12-

supra, at 866.  We think it would be a  great stretch to call
     

the tapes an abstract demonstration of scientific principles,

but the critical point  is not one of labels.   The issue for

us  is whether  the demonstration  is  sufficiently close  in

appearance to  the original accident  to create  the risk  of

misunderstanding by the jury, for  it is that risk that gives

rise to the special requirement to show similar conditions.5

     Here the test track demonstration was rife with the risk

of  misunderstanding.   Whatever  Fusco's counsel  or experts

said  to the jury about differing circumstances, the drama of

the filmed recreation could easily  overcome the logic of the

distinctions.   Our  case  is  scarcely  different  than  the

recreation  in Swajian  involving  a broken  rear  axle in  a
                      

similarly staged demonstration  by General Motors.   We there

affirmed  the  trial  judge's  exclusion  of  such  evidence,

pointing to  "the  sound and  broad discretion  of the  trial

judge" in policing  such videotaped evidence. Id. at  36.  We
                                                 

reaffirm here the principle and the result.

                             III.

     The second issue on appeal  concerns the decision of the

trial  judge to exclude  an additional videotape  prepared by

                    

     5Scientific principles,  when demonstrated  in a  fairly
abstract  way, are  quite  unlikely to  be confused  with the
events  on trial.   The more troublesome  cases, however, are
ones  like this one where some principles of some kind may be
demonstrated but  in a  fashion that looks  very much  like a
recreation of the event that gave rise to the trial.

                             -13-

General Motors  after the first  trial ended in a  hung jury.

This tape  was prepared on  October 2, 1993, and  provided to

Fusco on October  14, 1993, approximately three  months after

the  first trial and one  month before the  second.  The tape

shows a slow motion, close-up  impact fracture of a ball stud

filmed at close  range.  On the  tape one sees the  stud bend

and separate from the ball.  There is no commentary.

     After  receiving the  tape, Fusco  immediately moved  in
                                                             

limine to exclude it, together with  a newly created "survey"
      

of the accident  site that General Motors had  tendered.  The

district court  allowed the survey to  be used but ruled that

the tape would not be admissible, stating:

          With  regard  to  the importance  of  the
          exhibit  to  the   defendant,  the  Court
          cannot  fathom  how defendant  could  not
          present  a  complete  case  to  the  jury
          without  the videotape  as defendant  has
          already  done  so  at  the  first  trial.
          Finally,  the Court  does not  doubt that
          plaintiff would have a  difficult time to
          formulate  a  proper response  given  the
          obvious lack of time  before retrial.  It
          is primarily  for this  reason the  Court
          obviates  defendant  from  submitting the
          videotape exhibit.

     On  appeal,  General  Motors does  not  spend  much time

explaining the significance of the tape, saying only that  it

was "to show  how the  part in  question bends  prior to  and

during  an  overload  situation."   Instead,  General  Motors

argues with some force that the district judge has no general

authority  to  exclude  exhibits  merely  because  their last

                             -14-

minute  appearance will  inconvenience  or  burden the  other

side.    This exclusion,  says  General  Motors, was  not  an

exercise of the  court's accustomed power over  discovery but

an interference with  the right of counsel  to offer evidence

at trial.

     Of course, a trial court could readily exclude a witness

or  exhibit if  some previous  order had  set a  deadline for

identification and the proponent  had without adequate excuse

failed to list the witness or exhibit.  But here the deadline

for listing exhibits at the second trial did not expire until

one week before trial, well after the tape was tendered.  Nor

is there  any general rule prohibiting a  party from offering

new evidence  at a second  trial, although few  cases address

the  issue.   See  Lauritzen v.  Atlantic Greyhound  Corp., 8
                                                          

F.R.D. 237, 238  (E.D. Tenn. 1948), aff'd 182  F.2d. 840 (6th
                                         

Cir. 1950).  In fact, the district court here allowed General

Motors  to introduce  at  the second  trial  a newly  created

survey of the accident site.

     Nevertheless, we think  that the tape did  implicate the

district court's authority over discovery.   The tape was not

a stand alone exhibit: it made  sense only in the context  of

expert testimony to be offered by General Motors.   An expert

or experts would  have had to explain the  tape's meaning and

would have used it to bolster inferences drawn by the expert.

Indeed, even now it is not clear to us precisely how the tape

                             -15-

was expected  to help  General Motors'  experts, although  we

will   assume  that  it   was  either  intended   to  counter

plaintiffs' expert analysis or to make more plausible General

Motors'  account of  how  the ball  stud  retrieved from  the

accident was actually damaged.

     The  connection of the tape  to discovery now comes into

view.    Fusco's   discovery  had  included  a   request  for

production of "[a]ny and all  . . . videotapes" taken by, for

or for the benefit of Ulman, Willis, and "any and  all expert

consultants."   If the  tape had existed  when General Motors

first responded to  this request, the tape would  have had to

be  produced.   We  think  that the  duty  of supplementation

specified  in Fed.  R. Civ.  P. 26(e)  also required  General

Motors seasonably to produce any later developed videotape of

any importance intended for use by its expert at trial.

     The "duty to supplement" provisions are not  as clear as

they might be,  and the authorities are  surprisingly sparse.

A  party is  required  to supplement--that  is, update--prior

responses   only  in  limited  instances  but  they  include,

pertinently, responses  (1) concerning "the substance" of the

expert's testimony and  (2) where new information  exists and

failure  to amend  would  comprise  "a knowing  concealment."

Fed.  R. Civ.  P. 26(e)(1),  (2).   We  have read  Rule 26(e)

generously, in light  of its dual purposes, the "narrowing of

                             -16-

issues  and  elimination  of  surprise."    Johnson  v.  H.K.
                                                             

Webster, Inc. 775 F.2d 1, 7 (1st Cir. 1985).6
             

       We  think that  these  clauses  are  broad  enough  to

embrace the tape in  this case.  It was  closely connected to

the expert's testimony, it was not previously known to Fusco,

and   General  Motors  can   hardly  describe  the   tape  as

unimportant  since it claims  that the exclusion  of the tape

undermined the entire trial.  Thus we think that the tape was

covered  by General Motors'  obligation to produce  under the

discovery rules.   In our view--and this is the final step in

our reasoning--the  discovery obligation carries  with it the

implicit  authority of  the district  court  to exclude  such

materials when not timely produced even if there was no rigid
                         

deadline for production.

     There  is  no  suggestion that  General  Motors  delayed

unduly  if  one  counts  only  the  brief delay  between  the

creation of the tape and its tender to Fusco.   But practical

considerations  suggest that the authority of the trial judge

must  be  broader:  otherwise  it  would  count  as  adequate

supplementation to create a critical new expert exhibit a day

before trial and  tender it on the  morning of trial.   It is

                    

     6The   knowing-concealment  clause   does  not   require
fraudulent  intent; rather it is designed  to protect a party
who reasonably  believes "that  the change that  has made  an
answer no longer accurate is known to his opponent or that it
is a matter  of no importance."   Fortino v. Quasar  Co., 950
                                                        
F.2d 389, 396 (7th Cir. 1991).

                             -17-

common experience that experts,  like lawyers themselves, may

increase their  efforts as  trial approaches,  and we  do not

suggest any general  bar to an exhibit created  in good faith

for the expert after initial discovery.  But we do think that

where a discovery request for the expert's materials has been

made, the later attempt to  add new exhibits designed for the

expert's use at trial is subject to reasonable supervision by

the trial judge.

     This circuit adopted this very principle in Thibeault v.
                                                          

Square D Co., 960 F.2d 239, 245 (1st Cir. 1992).  The factual
            

differences  between that  case and  this one  relate to  the

sound  exercise of  the  authority  to  exclude and  not  its

existence.  We emphasize that  our ruling in Thibeault and in
                                                      

this  case rests  on  the existence  of a  specific discovery

request  and the  explicit duty  to supplement  it  in timely

fashion.  Absent some such obligation, we  agree with General

Motors  that courts  cannot ordinarily  tell  counsel not  to

offer evidence just because the other  side will be surprised

and disadvantaged.       Once   the   court's   authority  to

exclude here is conceded, its exercise in this case cannot be

faulted.   The  impact tape was  a technical  experiment made

known to Fusco barely  a month before trial.  To  prepare for

cross-examination might  have required  further discovery  by

Fusco of one  or more  of the defense  witnesses, as well  as

additional preparation by  Fusco's experts.  The  tape itself

                             -18-

is  pictures without words; even to determine the precise use

General Motors planned to make of it would have required more

information.  The  district court was  entitled to find  that

the tape would have compromised Fusco's pretrial preparations

and   that  the   supplementation  came   too   late  to   be

"seasonable."

                             IV.

     General Motors' remaining claim of error also relates to

the district court's authority over discovery.   At the first

trial  Fusco's  experts made  use  of  the  broken ball  stud

recovered  from Fusco's  car  and offered  Walson's testimony

based  on  his  examination  of  the  part  under  a scanning

electron microscope.   That part, in Fusco's  possession, was

available to General  Motors prior to the first  trial but it

chose not to make such an examination of its own.  In theory,

study of the  surface of the broken part might  cast light on

whether the part had broken from impact or fatigue.

     Taking  note of Walson's  testimony in the  first trial,

General  Motors in preparation for the second trial requested

that the  part, and an  additional Pontiac ball stud  used by

Walson for  comparison, be  made  available to  it.   General

Motors wanted  its own metallurgist  to make a  similar, non-

destructive  examination  by scanning  electron  microscope.7

                    

     7General  Motors proposed to have one of its first-trial
experts  conduct the examination  but, when  Fusco questioned
his qualifications,  General Motors proposed to  have another

                             -19-

Fusco refused to  produce the parts and General  Motors moved

to compel  production.  The  district court wrote  a ten-page

order denying General Motors' motion.  

     In its order, the court said that General Motors knew as

early as  May 1991 that  Fusco intended to offer  evidence of

examination  by scanning electron microscope.  The court also

said that the new examination  was intended as the  predicate

for new expert testimony by General Motors, testimony unknown

to Fusco when General Motors' experts  were deposed, and that

this last minute  addition imposed an unfair burden  on Fusco

on the eve of the second  trial.  The court also referred  to

General Motors' development of new evidence on the eve of the

first trial,  which the court  had permitted over  protest by

Fusco.   Finally, it  expressed concern  that General  Motors

sought  to overwhelm plaintiff  with its unlimited  legal and

financial resources.

     There is no doubt here of the district court's authority

to deny further discovery.   As noted above, no automatic bar

exists  against  new evidence  at  a  second  trial; but  the

discovery deadline  had long  since passed  and the  district

court had  no automatic  obligation to  reopen the  discovery

period.  E.g., Dabney v. Montgomery Ward &amp; Co., 761 F.2d 494,
                                              

                    

expert whose qualifications were conceded  participate in the
examination  and testify  at trial.   Whether  one  views the
testimony as  that of  a first-trial expert  or a  new expert
does not greatly affect the matter.

                             -20-

498  (8th Cir.),  cert. denied,  474  U.S. 904  (1985).   The
                              

matter  was one  for  the informed  discretion  of the  trial

judge, and the  breadth of that  discretion in managing  pre-

trial mechanics and  discovery is very great.   E.g., Fashion
                                                             

House, Inc.  v. K Mart Corp.,  892 F.2d 1076, 1082  (1st Cir.
                            

1989); Mack  v. Great  Atlantic &amp; Pacific  Tea Co.,  871 F.2d
                                                  

179, 186-87 (1st Cir. 1989).  Measured  against this standard

of review,  the district  court's quite  thorough explanation

for denying production easily passes muster.

     Our own review of the record does not suggest to us that

General Motors'  request was made  in bad faith  or reflected

any attempt  to abuse its  financial power.  Fusco  after all

was  seeking  $8  million,  and  defense  counsel  apparently

perceived in  the first trial  that the testimony  by Fusco's

expert about  the scanning  electron microscope  carried some

weight.  But it was primarily  for the trial judge to balance

the  factors, such  as  the timing  of  the request,  General

Motors'  earlier knowledge, the  possible burden on  Fusco of

preparing to confront a new expert, and the importance of the

testimony.   The balance struck  here by the trial  judge was

not an abuse of discretion.

     Affirmed. 
             

                             -21-
