Document ID: ./input/supremecourt_opinions/opinions/19pdf/18-1086_5ie6.pdf
Page Number: 9

Cite as:  590 U. S. ____ (2020) 

7 

Opinion of the Court 

Put  another  way,  claim  preclusion  “describes  the  rules
formerly known as ‘merger’ and ‘bar.’ ”  Taylor v. Sturgell, 
553  U. S.  880,  892,  n. 5  (2008).    “If  the  plaintiff  wins,  the 
entire claim is merged in the judgment; the plaintiff cannot 
bring a second independent action for additional relief, and 
the defendant cannot avoid the judgment by  offering new 
defenses.”  Wright & Miller §4406.  But “[i]f the second law-
suit involves a new claim or cause of action, the parties may 
raise assertions or defenses that were omitted from the first 
lawsuit even though they were equally relevant to the first
cause of action.”  Ibid. 

As the Second Circuit itself seemed to recognize, see 898
F. 3d, at 236–237, this Court has never explicitly recognized
“defense  preclusion”  as  a  standalone  category  of  res  judi-
cata, unmoored from the two guideposts of issue preclusion 
and claim preclusion.  Instead, our case law indicates that 
any such preclusion of defenses must, at a minimum, sat-
isfy  the  strictures  of  issue  preclusion  or  claim  preclusion. 
See, e.g., Davis v. Brown, 94 U. S. 423, 428 (1877) (holding 
that where two lawsuits involved different claims, preclu-
sion operates “only upon the matter actually at issue and 
determined in the original action”).2  The parties thus agree
that where, as here, issue preclusion does not apply, a de-
fense  can  be  barred  only  if  the  “causes  of  action  are  the 

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2 There may be good reasons to question any application of claim pre-
clusion to defenses.  It has been noted that in suits involving successive 
claims against the same defendant, courts often “assum[e] that the de-
fendant may raise defenses in the second action that were not raised in 
the first, even though they were equally available and relevant in both
actions.”  Wright & Miller §4414.  This is because “[v]arious considera-
tions, other than actual merits, may govern” whether to bring a defense, 
“such as the smallness of the amount or the value of the property in con-
troversy, the difficulty of obtaining the necessary evidence, the expense
of the litigation, and [a party’s] own situation.”  Cromwell v. County of 
Sac, 94 U. S. 351, 356 (1877).  Here, however, this Court need not deter-
mine when (if ever) applying claim preclusion to defenses may be appro-
priate, because a necessary predicate—identity of claims—is lacking.