Was the defendant's negligent act an actual cause of the plaintiff's harm?
這一課問的是：D 的過失行為，是否是 P 所受損害的「事實上的原因」 —— 過失四要件的第三關。
ActorChainObjectStandardConsequence
① Visual Scene
Actual Cause
本課的視覺化圖 — 同一套五色 Visual Grammar 表達核心結構。
Notice the diagram uses the same five-role colour grammar — Actor, Act, Object, Standard, Consequence.
② Core Terms
7 words you must own
本課術語。點擊卡片翻面看法律含義。
Tap a card to flip it.
③ Issue Meaning
What does this topic ask?
這一課問的是：D 的過失行為，是否是 P 所受損害的「事實上的原因」 —— 過失四要件的第三關。
"Actual Cause" really asks: Was the defendant's negligent act an actual cause of the plaintiff's harm?
Trigger words 觸發詞 — see these, think "Actual Cause":
but forwould not have happenedcausedled toresulted inchain of events
④ Expression Bank
How lawyers say it
不只是認識單詞，而是知道律師怎麼把它說出來。讀出聲音。
⑤ Rule Sentence
One exam-ready rule
先看 Core（核心要件），再切到 Full（完整考試句）。
A defendant's negligent act is an actual cause of the plaintiff's harm if the harm would not have occurred but for that act.; where two or more causes, each alone sufficient to produce the harm, combine, the but-for test is replaced by the substantial-factor test, and each cause that was a substantial factor is an actual cause.
Source: Legal English for U.S. Law · Torts Production Standard v1.0
⑥ Sentence Anatomy
Five colored parts — always
把規則句拆成 5 個彩色零件 — 同一套顏色，貫穿 16 科每一節 lesson。
Actor + Act
a defendant's negligent act
D 之過失行為
Chain
the chain of events
事件鏈
Object 對象
the plaintiff's harm
P 之損害
Standard 法律標準
the but-for test · substantial-factor test
但因/實質要素
Consequence 後果
actual cause is established
事實原因成立
同一套五個零件在 16 科每一句 rule 裡重複出現。
⑦ Casebook Snapshot
How U.S. courts teach this
美國法學院用案例教學。每節課看一個經典案例，只看法官最核心的 holding。
Anderson v. Minneapolis, St. Paul & Sault Ste. Marie Railway Co.
Minnesota Supreme Court, 1920 · the merging-fires case
Simplified Holding
Where a fire negligently set by the defendant merges with another fire of independent origin, and each fire alone would have been enough to destroy the plaintiff's property, the defendant's fire is still a cause if it was a substantial factor; a wrongdoer does not escape merely because another sufficient cause also existed.
Why It Matters Here
When but-for fails because two causes overlap, substantial-factor takes over so neither sufficient cause escapes.
兩個獨立足以致害的原因合併時，改用實質要素測試。
This is a simplified statement of the court's holding, written for study — not a quotation.
⑧ Mini IRAC
Your first legal analysis
用 IRAC 四步做最小法律分析。選出空格裡正確的詞。
Issue 法律問題
Was D's failure to repair a broken stairwell light an actual cause of P's fall on the dark stairs?
Rule 規則
A negligent act is an actual cause of harm if the harm would not have occurred but for that act.
Application 適用
D, a landlord, left the stairwell light broken for weeks; P fell on the unlit stairs at night. Because an act is an actual cause when the harm would not have occurred it, the fact that — means .
Conclusion 結論
Therefore, D's negligence was an actual cause of P's harm.
Application formula: Because [rule], the fact that [legalized fact] means [legal significance]. Always say what the fact means in law.
⑨ Common Mistakes
Where Chinese learners slip
這些是中文母語學習者最常踩的坑。
actual cause 和 proximate cause 是同一回事。
Actual is fact; proximate is scope/foreseeability.
前者問是不是；後者問應不應該。
D 的行為只要出現在事件鏈裡就算原因。
Must pass but-for: without the act, no harm.
須通過 but-for 測試。
有兩個原因時，D 就脫責。
Use substantial-factor test; D doesn't escape.
用實質要素測試，D 不脫責。
actual cause 是在問 D 有沒有過錯。
Fault is in breach; causation is purely factual.
過錯屬 breach 要件。
⑩ MBE Check
One quick multiple-choice check
用一道選擇題檢查你是否抓住了核心規則。
Two fires destroy P's barn. One was negligently started by D; the other had an unknown origin. Each fire alone would have been enough to burn the barn down. The fires merged before reaching the barn. Is D's fire an actual cause of the loss?
⑪ Mini Essay
Write one IRAC paragraph
寫一段 IRAC。寫完後再展開 model answer 對照。
Facts
D ran a red light and struck P's car in the intersection. P suffered a broken arm in the collision.
Call
Was D's act an actual cause of P's broken arm?
Your Task
Write one short IRAC paragraph — Issue, Rule, Application, Conclusion.
Issue
The issue is whether the facts satisfy the rule for Actual Cause.
Rule
A defendant's negligent act is an actual cause of the plaintiff's harm if the harm would not have occurred but for that act.
Application
D ran a red light and drove into P's car, and P broke her arm in the impact. Because an act is an actual cause when the harm would not have occurred but for it, the fact that there would have been no collision — and no broken arm — had D stopped at the light means D's act was a but-for cause of the injury.
Conclusion
Therefore, D's act was an actual cause of P's broken arm.
