Act of Third Parties in Tort Law

Law of Torts Complete LLB Notes

Act of Third Parties is an important topic under the General Defences in the Law of Torts. It is particularly significant in relation to the rule of strict liability under Rylands v Fletcher, where an independent act of a stranger may, in appropriate circumstances, break the chain of liability.

However, an important qualification is necessary: the act of a third party is not a universal defence to every tort claim. Whether it protects the defendant depends upon the nature of the tort, the defendant’s own duty, the foreseeability of the third party’s conduct, and the degree of control or relationship between the defendant and the third party.

This distinction is important for LL.B. students because the doctrine is often incorrectly stated as:

“If a third party caused the damage, the defendant is not liable.”

That statement is too broad.

The correct rule is more precise:

An independent, unforeseeable act of a third party over whom the defendant has no control may, in appropriate circumstances, relieve the defendant of liability; however, where the defendant had a duty to anticipate, prevent or control the third party’s conduct, the defence may fail.

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1. Meaning of Act of Third Parties

An act of a third party means an independent act or intervention by a person who is:

• not the defendant;
• not the defendant’s servant or agent acting within the relevant scope;
• not under the defendant’s control; and
• sufficiently independent that the defendant should not ordinarily be held responsible for that person’s conduct.

The person may also be described as a:

• stranger;
• third party; or
• independent intervening person.

For example, suppose A stores water in a reservoir in accordance with reasonable precautions. A stranger deliberately damages a part of the reservoir, causing an escape of water and damage to B’s property.

If the stranger’s conduct was independent and unforeseeable, A may be able to rely on the act of a third party as a defence under the traditional rule of strict liability.

2. Act of Third Party as a General Defence

The doctrine is traditionally discussed among the exceptions to the rule in Rylands v Fletcher.

The classic rule in Rylands v Fletcher imposes liability where a defendant:

1. brings something onto land;
2. collects and keeps it there;
3. makes a non-natural or special use of the land;
4. knows or ought to know that it is likely to cause mischief if it escapes; and
5. the thing escapes and causes damage.

One of the traditional exceptions is:

Act of a Stranger

Where the escape is caused solely by the independent act of a stranger over whom the defendant has no control, and the defendant could not reasonably have anticipated or guarded against the act, the defendant may avoid liability under the rule.

The principle is illustrated by Box v Jubb and Rickards v Lothian. (e-lawresources.co.uk)

3. Important Limitation — It Is Not a Defence to Every Tort

This is particularly important for your AspirixWriters notes.

The expression “Act of Third Parties” can be misleading if presented as a universal defence.

In negligence, for example, the defendant may still be liable where:

• the third-party conduct was foreseeable;
• the defendant created or increased the risk;
• the defendant had a duty to control the third party;
• the defendant knew of a particular danger;
• the defendant had assumed responsibility; or
• a special relationship existed between the defendant and the third party.

The House of Lords’ decision in Home Office v Dorset Yacht Co Ltd is an important illustration. The court recognised that a defendant may owe a duty to prevent harm caused by a third party where there is a sufficient relationship and the risk is foreseeable.

Therefore, students should not treat “Act of Third Party” as synonymous with “no negligence.”

4. Essential Conditions for the Defence

For an act of a third party to operate as a defence, the following factors are important.

1. The third party must be independent

The person should genuinely be a stranger to the defendant.

If the person is the defendant’s:

• employee;
• servant;
• agent; or
• person whose conduct is legally attributable to the defendant,

the defence may not be available.

2. The defendant must not have control over the third party

If the defendant has legal or practical control over the person, the argument becomes much weaker.

For example, an employer cannot ordinarily escape liability simply by describing an employee’s conduct as the act of a “third party.”

3. The act should be independent

The third party’s conduct must be an independent intervention rather than something arising naturally from the defendant’s own conduct.

4. The act should generally be unforeseeable

If the defendant could reasonably foresee that the third party would interfere with the dangerous thing, the defendant may be required to take precautions.

This is particularly important in modern applications of strict liability.

5. The defendant should not have been negligent in relation to the risk

If the defendant knew about the third party’s conduct but failed to take reasonable precautions, the defence may fail.

6. The third-party act must be sufficiently connected with the damage

The defendant must establish that the third party’s independent act was the real cause of the relevant escape or harm.

5. Cases

Box v Jubb — Leading Case

Box v Jubb (1879)

This is one of the classic authorities on act of a stranger under the rule in Rylands v Fletcher.

Facts

The defendant had a reservoir.

Another reservoir situated at a higher level was emptied by its owner through a drain connected with the defendant’s reservoir.

The resulting flow caused the defendant’s reservoir to overflow, damaging the claimant’s property.

Decision

The defendant was not liable.

The overflow resulted from the act of a third party over whom the defendant had no control.

The court considered that the defendant could not reasonably have been expected to anticipate the particular wrongful act of the stranger. (e-lawresources.co.uk)

Principle

An independent and unforeseeable act of a stranger may constitute a defence to liability under the rule in Rylands v Fletcher.

Exam Point

Box v Jubb → Act of stranger → no control + unforeseeable intervention → defence.

Rickards v Lothian

Rickards v Lothian [1913] AC 263; [1913] UKPC 1

This is another leading authority.

Facts

The defendant owned a building containing several tenanted floors.

An unknown person deliberately:

• blocked the waste pipes of a lavatory; and
• turned on the taps.

Water consequently overflowed and damaged the claimant’s goods on a lower floor.

The claimant sought to rely upon the principle of Rylands v Fletcher.

Decision

The Privy Council held that the defendant was not liable for the damage caused by the malicious act of the third party. The defendant had no knowledge or control over the stranger’s conduct. (High Court of Australia)

Principle

An independent malicious act by a stranger may prevent liability where the defendant had no reasonable basis to anticipate or prevent it.

The case also concerned the requirement of non-natural use of land under Rylands v Fletcher. The Privy Council regarded an ordinary domestic water supply as an ordinary use of land. (High Court of Australia)

Exam Point

Rickards v Lothian → malicious act of stranger + no control/foreseeability → no liability under Rylands.

Patel Maganbhai Bapujibhai v Patel Ishwarbhai Motibhai

Patel Maganbhai Bapujibhai v Patel Ishwarbhai Motibhai Gujrat High Court, 1983

This Indian decision is particularly useful for understanding the limitation on the defence.

The court discussed the traditional principle that the rule in Rylands v Fletcher does not ordinarily apply where damage is caused by the independent act of a third party.

However, the court emphasised an important qualification:

If the third-party act was one that the defendant ought reasonably to have foreseen and guarded against, the defendant may still be liable.

The case is therefore valuable because it prevents students from treating “third party” as an automatic answer.

Mukesh Textile Mills v H.R. Subramanya Sastry

Mukesh Textile Mills (P) Ltd. v H.R. Subramanya Sastry

The Indian court discussed the third-party exception under Rylands v Fletcher and referred to authorities including:

• Box v Jubb; and
• Rickards v Lothian.

The court distinguished an independent conscious act of a stranger from circumstances where the chain of events remained attributable to the defendant’s own conduct.

Importance

This is a useful Indian authority for explaining the requirement of an independent intervening act.

M.P. Electricity Board v Shail Kumari

M.P. Electricity Board v Shail Kumari (2002) 2 SCC 162

This is one of the most important Indian cases to include in this topic.

Facts

Jogendra Singh was riding a bicycle at night when he came into contact with a live electric wire lying on a public road.

The electricity authorities argued that the accident resulted from the illegal interference/pilferage of electricity by a third party.

Supreme Court’s approach

The Supreme Court rejected the attempt to avoid liability merely by attributing the accident to the third party.

The Court held that an electricity supplier dealing with a dangerous form of energy has a high responsibility to take safety measures.

The case is important because it demonstrates:

Where the third-party act was reasonably foreseeable or the defendant had a special responsibility regarding the dangerous activity, the act of a stranger may not provide a defence.

The Supreme Court treated the electricity supplier’s liability as strict in the circumstances.

Exam Point

M.P. Electricity Board v Shail Kumari → foreseeable third-party interference → defence rejected.

6. Why M.P. Electricity Board v Shail Kumari Is Important

This case provides a very useful contrast:

Rickards v Lothian

Third party acted maliciously and independently → defendant not liable.

M.P. Electricity Board v Shail Kumari

Third-party interference with electricity supply → defendant’s responsibility regarding dangerous electricity remained → defence unsuccessful.

Therefore:

The crucial question is not merely whether a third party was involved, but whether the defendant could reasonably have anticipated and guarded against the risk.

7. Act of Third Party and Negligence

The doctrine has a more complicated role in negligence.

Suppose:

A negligently leaves a dangerous object unsecured.

B, a stranger, interferes with it.

C is injured.

A cannot automatically say:

“B caused the injury, therefore I am not liable.”

The court may ask:

• Was B’s conduct foreseeable?
• Did A create the risk?
• Did A have a duty to prevent the interference?
• Was B’s conduct an independent intervening act?
• Did A know of previous similar conduct?

If the third-party intervention was reasonably foreseeable, A may remain liable.

8. Home Office v Dorset Yacht Co Ltd

Home Office v Dorset Yacht Co Ltd [1970]

This is an important case for understanding why third-party intervention does not automatically break causation.

Facts

Borstal trainees were under the supervision and control of Home Office officers.

Several trainees escaped and subsequently damaged the claimant’s yacht.

The Home Office argued that the damage was caused by the independent acts of the escaped trainees.

Decision

The House of Lords held that the circumstances could give rise to a duty of care on the part of the officers/Home Office because of the relationship of control and the foreseeable risk of damage.

Lord Reid’s judgment emphasised that the issue was not simply whether one person could ever be liable for another person’s acts; rather, the question was whether the defendant’s own negligence in failing to exercise appropriate control could create liability.

Principle

Where the defendant has a special relationship involving control over a third party and harm is reasonably foreseeable, the third party’s act may not break the chain of liability.

9. Control Imports Responsibility

A useful way to remember Home Office v Dorset Yacht is:

Control → Responsibility

Where A has:

• legal control;
• custody;
• supervision; or
• another special relationship

over B, A may owe a duty to persons who could foreseeably be harmed by B’s conduct.

The general principle is that a person ordinarily has no general duty to control another person’s conduct, but recognised special relationships can create such a duty.

10. Act of Third Party and Causation

The concept is also closely connected with causation.

If:

Defendant’s conduct → third-party intervention → damage

the court must determine whether the third-party intervention:

A. Was foreseeable

If yes, it may not break the chain.

B. Was independent and unforeseeable

It may break the chain.

C. Was deliberately caused by the defendant’s own negligence

The defendant is less likely to escape liability.

D. Occurred because the defendant had failed to exercise control

The defendant may remain liable.

11. Act of Third Party vs Act of God

These two defences should not be confused.

Thus:

Act of Third Party = human intervention

Act of God = extraordinary natural event

12. Act of Third Party vs Inevitable Accident

Inevitable Accident

The harm occurs despite reasonable care and could not reasonably have been prevented.

Act of Third Party

The immediate cause is the independent conduct of another person.

The same facts may sometimes involve both concepts, but they are legally distinct.

13. Act of Third Party vs Novus Actus Interveniens

These concepts are closely connected but should not be treated as identical.

Act of Third Party

Identifies who caused the intervening event.

Novus Actus Interveniens

Concerns whether the intervening event is sufficiently independent to break the chain of causation.

Therefore:

An act of a third party may constitute a novus actus interveniens, but every third-party act does not automatically break the chain of causation.

This distinction is important for your Part 2 structure.

14. When the Defence Will Usually Succeed

The defence is strongest where:

1. the third party is genuinely independent;
2. the defendant had no control over the third party;
3. the act was unforeseeable;
4. the defendant had no reason to anticipate it;
5. the defendant had taken reasonable precautions where relevant;
6. the third-party act was the immediate cause of the damage; and
7. the defendant did not create a situation requiring special protective measures.

15. When the Defence Will Fail

The defence may fail where:

1. The third-party conduct was foreseeable

The defendant should reasonably have anticipated the risk.

2. The defendant had control over the third party

For example, a custodial or supervisory relationship may create a duty.

3. The defendant created the dangerous situation

The defendant cannot always escape responsibility merely because another person later interfered.

4. The defendant knew of previous similar acts

Prior incidents may make future interference foreseeable.

5. The defendant failed to take reasonable precautions

Especially where the defendant was responsible for a dangerous activity.

6. The law imposes strict or absolute liability

In some statutory or hazardous-activity contexts, traditional third-party exceptions may not apply.

16. Strict Liability vs Absolute Liability

Strict Liability — Rylands v Fletcher

Traditional strict liability contains recognised exceptions, including the act of a stranger in appropriate circumstances.

Absolute Liability — M.C. Mehta v Union of India

The Indian Supreme Court developed the doctrine of absolute liability for enterprises engaged in hazardous or inherently dangerous activities.

The traditional exceptions to Rylands v Fletcher cannot simply be imported into the Indian doctrine of absolute liability.

“Act of third party is not always a defence to strict and absolute liability.”

17. Important Cases at a Glance

The last case is especially useful for understanding modern negligence and third-party wrongdoing. The House of Lords considered whether an owner of an empty cinema could be liable when vandals started a fire that spread to neighbouring properties and concluded that, on the facts, no sufficient duty arose. (Wikipedia)

18. Exam-Oriented Answer (Summery

What is Act of Third Party as a Defence in Tort Law?

Act of Third Party refers to an independent act of a stranger that causes the damage complained of by the claimant. Traditionally, under the rule of strict liability in Rylands v Fletcher, an independent and unforeseeable act of a stranger over whom the defendant has no control may constitute a defence.

In Box v Jubb, the defendant was not held liable where the escape of water resulted from the independent act of another reservoir owner. Similarly, in Rickards v Lothian, the defendant was not liable where a stranger maliciously interfered with the water system. (e-lawresources.co.uk)

However, the defence is not absolute. If the defendant could reasonably foresee the third-party conduct or had a duty to control or prevent it, liability may still arise. M.P. Electricity Board v Shail Kumari illustrates this principle in the context of electricity, while Home Office v Dorset Yacht Co demonstrates that a special relationship and control over third parties can create a duty of care.

Thus, the applicability of the defence depends upon independence, foreseeability, control, the defendant’s own duty, and the applicable form of liability.

23. Quick Revision Notes

Act of Third Party

Meaning:
Independent intervention by a stranger causing the damage.

Main relevance:
Traditional exception to Rylands v Fletcher.

Essential requirements:

• Independent stranger
• No control
• Unforeseeable conduct
• No reasonable opportunity to prevent it
• Third party is the effective cause of escape/damage

Leading Cases

Box v Jubb
→ Independent stranger’s act.

Rickards v Lothian
→ Malicious third-party intervention.

M.P. Electricity Board v Shail Kumari
→ Foreseeable third-party interference; defence rejected.

Home Office v Dorset Yacht
→ Control + foreseeable harm = possible duty.

One-line rule

An independent and unforeseeable act of a stranger may relieve a defendant from liability, but the defence fails where the defendant had a duty, control, knowledge or reasonable opportunity to prevent the third-party harm.

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FAQs — Act of Third Parties in Tort Law