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18  MAYO COLLABORATIVE SERVICES v. PROMETHEUS 

LABORATORIES, INC. 
Opinion of the Court 

ture  of  Intellectual  Property  Law  305–306  (2003)  (The 
exclusion from patent law of basic truths reflects “both . . .
the  enormous  potential  for  rent  seeking  that  would  be
created  if  property  rights  could  be  obtained  in  them  and
. . . the enormous transaction costs that would be imposed 
on would-be users [of those truths]”).

The  laws  of  nature  at  issue  here  are  narrow  laws  that 
may have limited applications, but the patent claims that
embody  them  nonetheless  implicate  this  concern.    They
tell  a  treating  doctor  to  measure  metabolite  levels  and  to 
consider the resulting measurements in light of the statis­
tical  relationships  they  describe.  In  doing  so,  they  tie  up
the  doctor’s  subsequent  treatment  decision  whether  that 
treatment  does,  or  does  not,  change  in  light  of  the  infer­
ence  he  has  drawn  using  the  correlations.    And  they
threaten to inhibit the development of more refined treat­
ment  recommendations  (like  that  embodied  in  Mayo’s
test),  that  combine  Prometheus’  correlations  with  later
discovered  features  of  metabolites,  human  physiology  or 
individual patient characteristics.  The “determining” step
too  is  set  forth  in  highly  general  language  covering  all 
processes that make use of the correlations after measur­
ing  metabolites,  including  later  discovered  processes  that 
measure metabolite levels in new ways.

We  need  not,  and  do  not,  now  decide  whether  were  the 
steps  at  issue  here  less  conventional,  these  features  of
the claims would prove sufficient to invalidate them.  For 
here,  as  we  have  said,  the  steps  add  nothing  of  signifi­
cance  to  the  natural  laws  themselves.  Unlike,  say,  a
typical  patent  on  a  new  drug  or  a  new  way  of  using  an
existing drug, the patent claims do not confine their reach
to particular applications of those laws.  The presence here 
of  the  basic  underlying  concern  that  these  patents  tie  up 
too  much  future  use  of  laws  of  nature  simply  reinforces
our conclusion that the processes described in the patents 
are  not  patent  eligible,  while  eliminating  any  temptation