Document ID: ./input/supremecourt_opinions/opinions/21pdf/19-1392_6j37.pdf/19-1392_6j37.pdf
Page Number: 61

Cite as:  597 U. S. ____ (2022) 

53 

Opinion of the Court 

not enjoyed by an identical fetus in a remote area of a poor
country?

In addition, as the Court once explained, viability is not 
really a hard-and-fast line.  Ibid.  A physician determining
a  particular  fetus’s  odds  of  surviving  outside  the  womb
must  consider  “a  number  of  variables,”  including  “gesta-
tional age,” “fetal weight,” a woman’s “general health and 
nutrition,” the “quality of the available medical facilities,” 
and  other  factors.    Id.,  at  395–396.  It  is  thus  “only  with
difficulty” that a physician can estimate the “probability” of 
a particular fetus’s survival.  Id., at 396.  And even if each 
fetus’s probability of survival could be ascertained with cer-
tainty, settling on a “probabilit[y] of survival” that should 
count as “viability” is another matter.  Ibid.  Is a fetus via-
ble with a 10 percent chance of survival?  25 percent?  50 
percent?  Can such a judgment be made by a State?  And 
can a State specify a gestational age limit that applies in all 
cases?  Or must these difficult questions be left entirely to 
the individual “attending physician on the particular facts 
of the case before him”?  Id., at 388. 

The viability line, which Casey termed Roe’s central rule, 
makes no sense, and it is telling that other countries almost 
uniformly  eschew  such  a  line.52   The  Court  thus  asserted 
raw judicial power to impose, as a matter of constitutional 
law,  a  uniform  viability  rule  that  allowed  the  States  less 
freedom to regulate abortion than the majority of western
democracies enjoy. 

d 
All in all, Roe’s reasoning was exceedingly weak, and ac-
ademic commentators, including those who agreed with the 

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52 According  to  the  Center  for  Reproductive  Rights,  only  the  United
States  and  the  Netherlands  use  viability  as  a  gestational  limit  on  the 
availability of abortion on-request.  See Center for Reproductive Rights, 
The  World’s  Abortion  Laws  (Feb.  23,  2021),  https://reproductiverights 
.org/maps/worlds-abortion-laws.