12 
Expert  Testimony. 
( Am.  Jour.  Pbarm. 
1     January,  190o. 
tion  is  one  of  pure  opinion,  for  the  facts  are  all  beyond  his  knowledge. 
It  is  evident  that  in  the  absence  of  complete  and  careful  observation 
the  facts  may  be  so  manipulated  as  to  give  apparent  basis  for  dis- 
crepant opinions.  One  set  of  circumstances  is  made  prominent  by 
witnesses  for  defence,  another  by  witnesses  for  prosecution.  Few, 
if  any,  scientifically  accurate  observations  have  been  made  ot  symp- 
toms. The  autopsy  may  have  been  defective  in  various  ways.  The 
testimony  of  witnesses  not  only  on  opposite  sides,  but  on  the  same 
side  may  be  contradictory  or  even  in  certain  particulars  self-destruc- 
tive, from  a  scientific  viewpoint.  The  physician  may  thus  be  inclined 
to  minimize  in  his  own  mind  certain  testimony,  which  nevertheless 
he  is  called  upon  in  his  sworn  opinion  to  give  credence  to.  Evi- 
dently when  he  cannot  form  a  positive  opinion,  it  is  his  duty  to  say 
so,  and  not  to  attempt  to  twist  dubious  or  insufficient  evidence  into 
the  support  of  a  partisan,  because  partial,  view.  Again,  an  expert 
is  forbidden  to  formulate  questions  which  he  is  to  be  called  upon  to 
answer,  and  yet  some  error  in  the  formulation  may  apparently  color 
his  testimony  otherwise  than  he  desires.  He  must  avoid  this  by 
so  formulating  his  answer  that  it  shall  tell  its  own  story  independ- 
ently of  the  question,  and  by  limiting  his  answer  so  that  it  may  be 
positive  only  so  far  as  the  facts  are  positive;  and  qualified  as  to 
uncertainty  or  probability  when  the  facts  so  demand. 
Many  other  difficulties  affecting  expert  testimony  on  pharma- 
cologic questions  might  be  stated,  but  those  discussed  seem  to  be 
the  main  ones,  and  perhaps  if  they  can  be  averted  the  others  will 
to  a  large  extent  disappear. 
In  addition  to  the  practice  of  controlled  examinations  and  exhi- 
bition of  results  already  alluded  to,  I  have  elsewhere  suggested  a 
method  that  would  do  away  with  our  main  difficulties,  but  this 
method  is  not  likely  to  be  adopted  for  many  years,  if  at  all.  It  is 
too  simple  and  direct.  That  method  is  the  submission  of  purely 
scientific  questions  to  a  commission  of  experts,  who  shall,  in  ad- 
vance of  the  jury  trial,  hear  the  relevant  testimony  as  to  matters  of 
fact,  including  the  methods  and  results  of  any  scientific  examinations, 
but  no  mere  opinions  from  witnesses — opinions  being  put  forth  by 
experts  frankly  appearing  as  advocates,  and  arguing  upon  the  testi- 
mony submitted.  Such  a  commission  could  submit  to  the  court  a 
report  or  reports,  which  could  thus  become  part  of  the  evidence 
heard  by  the  jury  that  has  to  find  the  verdict,  and  before  whom  no 
expert  should  appear  as  witness. 
