Document ID: ./input/supremecourt_opinions/opinions/23pdf/22-899_97be.pdf
Page Number: 34

Cite as:  602 U. S. ____ (2024) 

3 

ALITO, J., concurring in judgment 

admitted  expert  testimony  about  the  seaworthiness  of  a
ship based on a survey conducted when the expert was not 
present.  Thornton v. Royal Exchange Assurance Co., Peake 
37,  38,  170  Eng.  Rep.  70,  71  (N.  P.  1790).    Similarly,  an
early-19th century decision allowed ship surveyors to tes-
tify to  the seaworthiness of a vessel they had never seen. 
Beckwith v. Sydebotham, 1 Camp. 116, 170 Eng. Rep. 897 
(N. P. 1807).  The opposing party objected that the experts
did not know the underlying facts to be true, but the court 
admitted  their  opinions  because  the  experts’  technical
knowledge could assist the jury.  Ibid.  The fact that “the 
truth of the facts stated to them was not certainly known”
went to the weight of the testimony, not its admissibility. 
Ibid. 

Throughout the 19th and into the 20th century, experts
generally testified in the form of an opinion in response to 
a hypothetical question.  An attorney would ask an expert 
to  assume  that  certain  facts  were  true  and  would  then 
query whether a particular conclusion could conceivably fol-
low.  See 3 S. Saltzburg, M. Martin, D. Capra, & J. Berch, 
Federal  Rules  of  Evidence  Manual  §703.02[1]  (13th  ed. 
2023).

This procedure was highly artificial because it bore little 
resemblance to the way in which experts actually form opin-
ions.  And the procedure surely did not conform to the way
lay jurors think and speak. 

The procedure’s aim was to prevent a jury from jumping 
to the conclusion that the facts packed into the hypothetical 
were  true,  but  it  is  questionable  whether  the  practice
achieved that objective.  For instance, here is the question 
that defense counsel asked a psychiatric witness in Charles 
Guiteau’s trial for murdering President Garfield: 

“Q. . . . Assume it to be a fact that there was a strong
hereditary taint of insanity in the blood of the prisoner 
at the bar; also that at about the age of thirty-five years