CACI No. 431. Causation: Multiple Causes

Judicial Council of California Civil Jury Instructions (2023 edition)

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431.Causation: Multiple Causes
A person’s negligence may combine with another factor to cause harm. If
you find that [name of defendant]’s negligence was a substantial factor in
causing [name of plaintiff]’s harm, then [name of defendant] is responsible
for the harm. [Name of defendant] cannot avoid responsibility just
because some other person, condition, or event was also a substantial
factor in causing [name of plaintiff]’s harm.
New September 2003
Directions for Use
This instruction will apply only when negligence is the theory asserted against the
defendant. This instruction should be modified if the defendant is sued on a theory
of product liability or intentional tort.
Sources and Authority
‘Where several persons act in concert and damages result from their joint tort,
each person is held for the entire damages unless segregation as to causation can
be established. Even though persons are not acting in concert, if the results
produced by their acts are indivisible, each person is held liable for the whole.”
(Hughey v. Candoli (1958) 159 Cal.App.2d 231, 240 [323 P.2d 779].)
“In cases where concurrent independent causes contribute to an injury, we apply
the ‘substantial factor test of the Restatement Second of Torts, section 423,
which subsumes traditional ‘but for causation.” (State Dept. of State Hospitals v.
Superior Court (2015) 61 Cal.4th 339, 352 fn. 12 [188 Cal.Rptr.3d 309, 349 P.3d
“A defendant’s negligent conduct may combine with another factor to cause
harm; if a defendant’s negligence was a substantial factor in causing the
plaintiff’s harm, then the defendant is responsible for the harm; a defendant
cannot avoid responsibility just because some other person, condition, or event
was also a substantial factor in causing the plaintiff’s harm; but conduct is not a
substantial factor in causing harm if the same harm would have occurred without
that conduct.” (Yanez v. Plummer (2013) 221 Cal.App.4th 180, 187 [164
Cal.Rptr.3d 309].)
“We are also not persuaded CACI No. 431 confused the jury or diluted the
standard for causation. The [defendants] conflate the legal concepts of substantial
factor for causation and concurrent cause. CACI No. 431 is necessary to explain
to the jury a ‘plaintiff need not prove that the defendant’s negligence was the
sole cause of plaintiff’s injury in order to recover. Rather it is sufficient that
defendant’s negligence is a legal cause of injury, even though it operated in
combination with other causes, whether tortious or nontortious.’ (Uriell v.
Regents of University of California (2015) 234 Cal.App.4th 735, 746−747 [184
Cal.Rptr.3d 79] [CACI No. 431 properly explained concurrent substantial causes
to the jury].)
“For there to be comparative fault there must be more than one contributory or
concurrent legal cause of the injury for which recompense is sought.” (Doupnik
v. General Motors Corp. (1991) 225 Cal.App.3d 849, 866 [275 Cal.Rptr. 715].)
“Because we conclude that, in this case, in which causation was the most critical
contested issue and in which there was substantial evidence of multiple causes of
[decedent]’ s death, the trial court improperly [refused to instruct] the jury with
respect to concurrent causation . . . .” (Logacz v. Limansky (1999) 71
Cal.App.4th 1149, 1152 [84 Cal.Rptr.2d 257].)
“Clearly, where a defendant’s negligence is a concurring cause of an injury, the
law regards it as a legal cause of the injury, regardless of the extent to which it
contributes to the injury.” (Espinosa v. Little Company of Mary Hospital (1995)
31 Cal.App.4th 1304, 1317-1318 [37 Cal.Rptr.2d 541], original italics.)
Secondary Sources
6 Witkin, Summary of California Law (11th ed. 2017) Torts, § 1344
California Tort Guide (Cont.Ed.Bar 3d ed.) § 1.16
1 Levy et al., California Torts, Ch. 2, Causation, § 2.11 (Matthew Bender)
4 California Trial Guide, Unit 90, Closing Argument, § 90.89 (Matthew Bender)
California Products Liability Actions, Ch. 7, Proof, § 7.06 (Matthew Bender)
33 California Forms of Pleading and Practice, Ch. 380, Negligence (Matthew
16 California Points and Authorities, Ch. 165, Negligence, §§ 165.280-165.284
(Matthew Bender)

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