Factual causation andadequate causation
KAGAYAMA Shigeru
Professor of Law, Meijigakuin University

KAGAYAMA Shigeru, 20161

Issues on factual andadequate causation
Issues of factual causation
Issue 1
 Issue of understanding the principle“b will not occur without a (conditio sine qua non)”applied to examine the existence of factual causation

Issue of adequate causation
Issue 2Issues of clarifying the differences between factual and adequate
causation

Issue 3
Interpretation of the relationship between Article 416 of the Civil
Code and adequate causation theory
KAGAYAMA Shigeru, 20162

Issue 1
Factual causation


Through the “conditio sine qua non” test method, or“‘B’ will not occur without ‘A’, the factual causation is
judged, “existing or not”.
Question 1: Using the factual causation test method, choose thecorrect ones in the following examples (multiple answer is possible)(a) The premise ““if wind blows, pipe fitters make profit” is an example ofthe factual causation.
(b) The premise “no smoke without fire”. The source of smoke comes fromfire is an example of the factual causation(c) Both Kinohorumu medicine and virus were doubted as source of
Subacute-Myelo-Optico-Necuropathy disease. After suspending thecirculation of Kinohorumu, the disease stopped spreading. The proof that
there is a relationship between Kinohorumu medicine and Subacute-MyeloOptico-Necuropathy disease is an example of the factual causation.

KAGAYAMA Shigeru, 20163

Explanation of issue 1（1/3）
Factual causation test method
Within the test method “b will not occurwithout a” (or conditio sine qua non) used todecide the existence of factual causation
When circumstance a is eliminated, consequence b will occur
or not is assumed as follows:
If consequence b does not occur, a is the causer. In otherwords, there is a causality between a and b
 If consequence b still occurs, a is not the causer. In otherwords, there is not a causality between a and b

In order to decide if there is a factual causation ornot, we have first to use the test method. However,it should be noted that the test result is not alwayscorrect.
KAGAYAMA Shigeru, 20164

Explanation of issue 1 Main
points of conditio sine qua nonTo understand whether acauses b or not theapplication of the test
method “without a, will boccur or not” isconsidered “oppositereverse” logical test inlogic. This logical test is
not equivalent to theoriginal assumption.
The solely correct meaning of
this test method is that only acauses b (a?b).
In cases where several otherevents in addition to a cause b,
for example, in joint tortious
acts, the application of this testmethod is risky.

a → breverse￢a → ￢bconverse

contraposition

converseb → areverse￢b → ￢a

KAGAYAMA Shigeru, 20165

Explanation of issue 1（3/3）
Conclusions






Because the premise “if wind blows, pipe fitters makeprofit” is an “a-->b” premise, it is not included in thereverse conditio sine qua non test.
The reverse premise of the premise “smoke comes from fire” is “no fire no smoke.”
That means the premise “no fire no smoke” is the application of the conditio sinequa non test to prove that “the cause of smoke is fire.”
Truly, the premise “no fire no smoke” is not the reverse premise of the premise“there is smoke, there is fire” but a contraposition one. However, when considering
the original premise “there is fire, there is smoke,” under the sine qua non test, thepremise “no fire no smoke” is its reverse premise.
In the Subacute-Myelo-Optico-Necuropathy disease case, since the circulation ofKinohorumu medicine was stopped, there occurred no such disease case. So there
is a factual causation between the medicine intake and the disease outbreak.

KAGAYAMA Shigeru, 2016

6

How to prove thecausation A and B?
subacute myelo-optico-neuropathy

Quinoform(A1)
Pre-Probability0.5

Conditional
Probability0.5

Virus(A2)Pre-Probability0.5

Conditional
Probability0.01

Post-ProbabilityA1 =0.5×0.5
0.5×0.5+0.5×0.01≒ 0.98Post-ProbabilityA2 =0.5×0.01
0.5×0.5+0.5×0.01≒ 0.02KAGAYAMA Shigeru, 2016

Result(B)SMON

7Issue 2
Adequate causation (1)If factual causation is established by thetest method“without a, b will not occur”
the scope of causality is too broad.
Therefore, in order to limit the broad
scope of causation, it was proposed that,within the factual causation, only adequateor, in other words, legal causation ispermissible.
 The proposal made by J. von Kries under
his adequate causation theory


KAGAYAMA Shigeru, 20168

Issue 2
Adequate causation (1)Question 2: to explain the differences between factual
causation and adequate causation, several following
appropriate examples are given. Decide which example isrelevant to each type of causation (multiple answer ispossible).
(a) A woman gave birth to a child. 15 years later, the childcommitted murder.
(b) A wagoner, by his carelessness, turned his car to the left sideof instead of the right one at the crossroad. Unfortunately, athunder stroke on the wagon causing dead to passengers.
(c) The captain mistakenly handled the airplane driving it into theairspace of a non-diplomatic-relation country. The airplane wasattacked and the entire passengers died.
KAGAYAMA Shigeru, 20169Explanation of Question 2（1/3）
Example (a) is a frequently cited example in German
textbooks on criminal law. Applying the test method“without a there is no b” we see there is a factualcausation.
 However, according to statistics, there is no adequate
relation between the probability of producing
murderers with the growth or decrease rate ofchildbirth. Childbirth does not contribute to theincrease in number of murderers.
 Therefore, there is no adequate causation between
the giving birth action and the murderous act.
 As a result, we can say that example (a) is anappropriate example distinguishing factual causation
with adequate causation.
KAGAYAMA Shigeru, 201610

Explanation of Question 2（2/3）
Example (b) is a famous example of the author of theadequate causation theory, Kris. Similar to example (a)in the sense that if we apply the test method “without athere is no b” we see there is a factual causation.
 However, according to meteorology, no matter what thewagoner turns his car left or right, the probability ofthunder strikes is the same. The driving of his car to theleft side does not contribute to the increase ofprobability of the thunder strike.
 Therefore, There is no adequate causation between themisjudging of the wagoner and the thunder strike.
 As a result, we can say that example (b) is also anappropriate example distinguishing factual causation
with adequate causation.
KAGAYAMA Shigeru, 201611

Explanation of issues 2（3/3）
This example is a development from the mistake of thewagoner in the above example to the mistake of thecaptain. Also in this example there is a factual causation
if we apply the test method “without a there is no b.” What is worse is that as the plane having freely entereda non-diplomatic-relation country, we can realize theprobability of being attacked is high.
 Therefore, in case that the captain mistakenly drove theplane into a non-diplomatic-relation country, then wasattacked causing dead to passengers there was aadequate causation.
 As a result, we can say that example (c) is an
inappropriate example distinguishing factual causation
with adequate causation.
KAGAYAMA Shigeru, 201612

Explanation of issues 3Rules of the Anglo-Saxon system from
Hadley v. Baxendale (1854)

Ordinary damageRegarding the claim forcompensation, foreseeability is not
required (Article 416 para. 1)
 Special damageRegarding the claim forcompensation, forseeability is required(Article 416 para. 2)


KAGAYAMA Shigeru, 201613

How to calculate partial
causation ?
Industrial mercury(A1)Pre-Probability 00.8

Conditional
Probability0.5

Natural mercury(A2)Pre-Probability 00.2

Conditional
Probability0.25

Result(B)Minamata

Post-ProbabilityA1 =0.8×0.5
0.8×0.5+0.2×0.25≒ 0.89Post-ProbabilityA2 =0.2×0.25
0.8×0.5+0.2×0.25≒ 0.11KAGAYAMA Shigeru, 201614

How to calculate partial
causation ?
Defective Structue(A1)Pre-Probability0.5
Quake-Proof Structure(A2)Pre-Probability0.5

Conditional
Probability0.6
Conditional
Probability0.1

Result(B)Collapse

Post-ProbabilityA1 =0.5×0.6
0.5×0.6+0.5×0.1≒ 0.86

Post-ProbabilityA2 =0.5×0.1
0.5×0.6+0.5×0.1≒ 0.14KAGAYAMA Shigeru, 201615

How to calculate partial
causation ?
Defective Management(A1)Pre-Probability0.6
Proper Management(A2)Pre-Probability0.4

Conditional
Probability0.6
ConditionalProbability0.5

Result(B)Bus
Downfall

Post-ProbabilityA1 =0.6×0.6
0.6×0.6+0.4×0.5≒ 0.64Post-ProbabilityA2 =0.4×0.5
0.6×0.6+0.4×0.5≒ 0.36KAGAYAMA Shigeru, 201616

Case Law on adequate
causation in Japan 1/2


1. Affirmative caseJudgment of Supreme Court, March 24,2000 (Dentsu case)

2. Negative caseJugdment of Supreme Court, December 20,
1999

KAGAYAMA Shigeru, 201617

1. Affirmative case 1/2
Judgment of Supreme Court, March 24, 2000(Dentsu case)1. In a case where A, an employee, who worked in a major
advertising company became chronically depressed andcommitted suicide after working long overtime for more thana year, A was working under a general and comprehensive
business instruction to finish the given work within the time
limit, and had no choice but to do long overtime work on acontinuous basis as mentioned above. A's superiors were
aware that A was constantly working excessively long hours
and that his state of health had deteriorated but failed to takemeasures to alleviate the workload of A, and as a result, A
became mentally and physically exhausted, which triggered
chronic depression and as the state of depression deepened,
extemporaneously committed suicide. Under suchcircumstances, the employer is liable for compensation based
upon Article 715of the Civil Code.
KAGAYAMA Shigeru, 201618

1. Affirmative case 2/2
Judgment of Supreme Court, March 24, 2000
(Dentsu case)

2. In a claim for compensation based upon theinfliction of mental or physical harm on an employee,
where the character of the employee and the resulting
manner of the execution of work had contributed tothe occurrence or expansion of the damage, unless thecharacter of the employee is outside the scope which isnormally expected in employees involved in similar
work, when determining the amount of compensation,
the court cannot take into account the character of theemployee and similar factors as a mental factor byapplying, with the modification, Article 722, paragraph
2 of the Civil Code.
KAGAYAMA Shigeru, 201619

2. Negative caseJugdment of Supreme Court, December 20,
1999
In cases where a victim of a traffic accidentwho was in need of care after the accident,
later died from another cause, it is not
permissible to claim the cost of the care during
the period after the death as loss emanatingfrom the traffic accident.
KAGAYAMA Shigeru, 201620

Calculation of comparative negligencein case bicycle and motorcar(1/2)
Comparative negligence of bicycle is 20%
in case there is no excess of speed of bicycle

TAXI

KAGAYAMA Shigeru, 201621

Calculation of comparative negligencein case bicycle and motorcar(2/2)
Comparative negligence of bicycle is 30%
in case there is excess of speed of bicycle

TAXI

KAGAYAMA Shigeru, 2016

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KAGAYAMA Shigeru, 201623