Document ID: ./input/supremecourt_opinions/opinions/23pdf/22-899_97be.pdf
Page Number: 20.0

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

17 

Opinion of the Court 

on  the  truth  of  Rast’s  factual  statements.    Longoni  could
opine that the tested substances were marijuana, metham-
phetamine,  and  cannabis  only  because  he  accepted  the 
truth of what Rast had reported about her work in the lab—
that  she  had  performed  certain  tests  according  to  certain
protocols and gotten certain results.  And likewise, the jury 
could credit Longoni’s opinions identifying the substances 
only because it too accepted the truth of what Rast reported 
about her lab work (as conveyed by Longoni).  If Rast had 
lied about all those matters, Longoni’s expert opinion would 
have counted for nothing, and the jury would have been in
no position to convict.  So the State’s basis evidence—more 
precisely,  the  truth  of  the  statements  on  which  its  expert
relied—propped up its whole case.  But the maker of those 
statements was not in the courtroom, and Smith could not 
ask her any questions.

Approving  that  practice  would  make  our  decisions  in 
Melendez-Diaz and Bullcoming a dead letter, and allow for 
easy  evasion  of  the  Confrontation  Clause.    As  earlier  de-
scribed, those two decisions applied Crawford in “straight-
forward” fashion to forensic evidence.  Melendez-Diaz, 557 
U. S., at 312; see Bullcoming, 564 U. S., at 659–661; supra, 
at 3–5.  The first prevented the introduction of a lab ana-
lyst’s testimonial report sans lab analyst.  The second re-
fused to accede to the idea that any old analyst—i.e., a sub-
stitute who had not taken part in the lab work—would do.
Arizona offers only a slight variation.  On its view, a surro-
gate analyst can testify to all the same substance—that is, 
someone  else’s  substance—as  long  as  he  bases  an  “inde-
pendent opinion” on that material.  And that is true even if, 
as here, the proffered opinion merely replicates, rather than 
somehow  builds  on,  the  testing  analyst’s  conclusions.    So 
every  testimonial  lab  report  could  come  into  evidence 
through  any  trained  surrogate,  however  remote  from  the 
case.  And no defendant would have a right to cross-examine 
the testing analyst about what she did and how she did it