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12  MAYO COLLABORATIVE SERVICES v. PROMETHEUS 

LABORATORIES, INC. 
Opinion of the Court 

equation into the process as a whole.  Those steps included
“installing  rubber  in  a  press,  closing  the  mold,  constantly 
determining  the  temperature  of  the  mold,  constantly  re- 
calculating  the  appropriate  cure  time  through  the  use  of 
the  formula  and  a  digital  computer,  and  automatically
opening  the  press  at  the  proper  time.”    Id.,  at  187.  It 
nowhere  suggested  that  all  these  steps,  or  at  least  the
combination  of  those  steps,  were  in  context  obvious,  al­
ready in use, or purely conventional.  And so the patentees
did  not  “seek  to  pre-empt  the  use  of  [the]  equation,”  but 
sought “only to foreclose from others the use of that equa­
tion  in  conjunction  with  all  of  the  other  steps  in  their
claimed  process.” 
  These  other  steps  apparently
added  to  the  formula  something  that  in  terms  of  patent
law’s  objectives  had  significance—they  transformed  the 
process into an inventive application of the formula.

Ibid.

The  process  in  Flook  (held  not  patentable)  provided  a 

method  for  adjusting  “alarm  limits”  in  the  catalytic  con­
version  of  hydrocarbons.    Certain  operating  conditions
(such as temperature, pressure, and flow rates), which are
continuously  monitored  during  the  conversion  process,
signal  inefficiency  or  danger  when  they  exceed  certain 
“alarm  limits.”  The  claimed  process  amounted  to  an  im­
proved system for updating those alarm limits through the
steps  of:  (1)  measuring  the  current  level  of  the  variable, 
e.g., the temperature; (2) using an apparently novel math­
ematical  algorithm  to  calculate  the  current  alarm  limits; 
and (3) adjusting the system to reflect the new alarm-limit
values.  437 U. S., at 585–587. 

The Court, as in Diehr, pointed out that the basic math­
ematical  equation,  like  a  law  of  nature,  was  not  patenta­
ble.  But  it  characterized  the  claimed  process  as  doing 
nothing other than “provid[ing] a[n unpatentable] formula
for  computing  an  updated  alarm  limit.”    Flook,  supra,  at 
586.  Unlike the process in Diehr, it did not “explain how
the variables used in the formula were to be selected, nor