Rylands v Fletcher defences | OCR A-Level Law
For Specification H418
OCR A-Level Law | Free Revision Notes
Estimated study time: 45–55 minutes
This Rylands v Fletcher defences A-Level Law revision page explains the defences that may prevent a defendant from being liable even where the basic requirements of the tort appear to be established. OCR H418 expressly requires knowledge of the defences available in Rylands v Fletcher. You will study act of a stranger, act of God, volenti non fit injuria, common benefit and damage caused through the claimant's fault, then practise applying them to factual scenarios and reaching supported conclusions.
Learning Objectives 🎯
By the end of this revision page, you should be able to:
Explain the principal defences available to a claim under Rylands v Fletcher.
Explain the defence of act of a stranger.
Explain act of God, volenti non fit injuria, common benefit and claimant's fault.
Identify which defence is raised by the facts of a scenario.
Apply the relevant defence rather than simply stating it.
Reach a supported conclusion on whether a defendant remains liable.
Revision Notes 📚
Rylands v Fletcher defences A-Level Law revision overview
Before considering a defence, first establish whether the claimant has a prima facie claim under Rylands v Fletcher [Lesson 129. Rylands v Fletcher].
The basic liability analysis asks whether:
the defendant brought onto and accumulated something on land under their control
the thing was likely to cause mischief if it escaped
the use of land was extraordinary and unusual in the circumstances of the time and place
the thing escaped from the defendant's control to the claimant's land
the escape caused reasonably foreseeable actionable damage.
Only once liability appears to be established should you ask whether a defence prevents recovery.
OCR's specification expressly includes defences specific to claims connected to Rylands v Fletcher. OCR's specimen mark scheme identifies the following available defences:
Defence | Authority identified by OCR |
Act of a stranger | Perry v Kendricks Transport |
Act of God | Nicholls v Marsland |
Volenti non fit injuria | Peters v Prince of Wales Theatre |
Common benefit | Dunne v North West Gas Board |
Damage caused through claimant's fault | Eastern & South African Telegraph v Cape Town Tramways |
Act of a stranger
The act of a stranger defence arises where an independent third party causes the escape.
The relevant authority is Perry v Kendricks Transport. OCR's 2025 mark scheme explains that where a stranger over whom the defendant has no control causes the escape, there may be a defence.
However, simply identifying that another person interfered with the accumulated thing is not enough.
A crucial question is whether the defendant could have:
anticipated the stranger's conduct, or
guarded against it.
OCR's 2025 examiner report explained that this issue could lead to different, equally supportable conclusions depending on the facts.
Applying act of a stranger
Suppose:
Arjun stores a large quantity of chemicals in a secure locked building. An unknown person breaks into the building, deliberately opens a tank and causes the chemical to escape onto neighbouring land. There was nothing to indicate that such interference was likely.
The defendant could argue:
the escape was caused by a third party
that person was outside Arjun's control
there was no obvious reason for Arjun to anticipate the interference
reasonable precautions had already been taken.
This gives Arjun a strong argument for the act of a stranger defence.
Now change the facts:
Arjun stores the chemical in an unlocked container beside a public footpath. Local people have repeatedly entered the site and interfered with equipment.
The outcome could be different.
Although a stranger eventually causes the escape, the facts suggest that further interference might have been anticipated or guarded against.
📌 Exam technique: Do not write "a stranger caused it, so the defence succeeds". Ask whether the defendant had control over the stranger and whether the interference could reasonably have been anticipated or guarded against.
The 2025 OCR example
OCR tested the act of a stranger defence directly in 2025.
Charlie stored battery acid in an old oil drum outside his garage. Local teenagers interfered with the drum and one pulled it over, causing the acid to escape onto neighbouring property.
OCR accepted two routes:
Charlie might succeed because CCTV established that a stranger caused the escape.
Alternatively, the defence might fail because Charlie could arguably have guarded against the interference by not leaving the acid outside.
This is a great example of why AO2 is not simply about finding one predetermined answer.
A supported conclusion matters more than making an unsupported assertion.
Act of God
Another defence is act of God.
OCR identifies Nicholls v Marsland as the relevant authority.
This defence concerns an escape caused by an exceptional natural event rather than the defendant's own conduct.
Typical scenario clues include an unusual natural event such as an extreme storm.
OCR's specimen assessment illustrates the issue using a serious storm which affected a tank of used oil, while also identifying act of God as an available Rylands v Fletcher defence.
Applying act of God
Suppose:
Idris has accumulated a large quantity of liquid on his land. An exceptionally severe storm causes the containment system to overflow, sending the liquid onto neighbouring land.
The facts raise act of God.
A good answer should:
identify the defence
cite Nicholls v Marsland
link the natural event directly to the escape
decide whether the defendant can rely on the event to avoid liability.
Do not simply say:
"There was bad weather, therefore act of God applies."
The facts must support the argument that it was the natural event which caused the escape.
Act of God and act of a stranger compared
These defences can be kept separate by asking what caused the escape.
Cause of escape | Possible defence |
Independent third-party interference | Act of a stranger |
Exceptional natural event | Act of God |
Claimant's own conduct | Claimant's fault |
Identifying the immediate cause of the escape is therefore an excellent starting point in a problem question.
Volenti non fit injuria
Volenti non fit injuria is commonly shortened to volenti and concerns the claimant's consent.
OCR includes volenti non fit injuria as a general tort defence and also identifies it as an available defence to Rylands v Fletcher.
The relevant Rylands authority identified by OCR is Peters v Prince of Wales Theatre.
The defence becomes relevant where the facts indicate that the claimant consented to the relevant situation or risk.
Applying volenti
Suppose:
Two neighbouring occupiers agree that a large storage installation will be placed on one property for a purpose they have both accepted.
If an escape later occurs, facts showing genuine consent may raise volenti.
The important exam question is:
Is there evidence that the claimant actually consented?
Do not infer consent merely because the claimant knew that something was stored nearby.
The broader operation of this defence is consolidated later in volenti and land-specific defences [Lesson 139. Volenti and land-specific defences].
Common benefit
Common benefit is another defence specifically identified in OCR's specimen Rylands v Fletcher mark scheme.
The relevant authority is Dunne v North West Gas Board.
The defence concerns circumstances in which the relevant accumulation exists for the common benefit of both parties.
Applying common benefit
Suppose an arrangement involving the accumulated thing exists for the benefit of both the claimant and defendant.
The defendant may be able to argue that the claimant cannot successfully rely on Rylands v Fletcher where the accumulation was maintained for their common benefit.
In a scenario, look for explicit facts showing that:
both parties obtain the benefit
the arrangement is not simply for the defendant's individual advantage.
⚠️ Do not confuse common benefit with the broader idea that an activity benefits society generally.
The OCR source identifies common benefit as a specific Rylands defence. It is the shared benefit between the relevant parties that should trigger consideration of this defence.
Damage caused through the claimant's fault
A defendant may also rely on the fact that the damage was caused through the claimant's own fault.
OCR identifies Eastern & South African Telegraph v Cape Town Tramways as authority for this defence.
The key idea is that the claimant should not be able to impose Rylands liability on the defendant where the claimant's own conduct has caused the damaging event.
Applying claimant's fault
Suppose:
Leila's neighbour stores a large quantity of liquid in a secure tank. Leila enters the neighbour's property and deliberately damages the tank. The liquid escapes back onto Leila's own land and damages her greenhouse.
The defendant has a strong argument that the damage resulted from Leila's own fault.
The important factual link is:
claimant's conduct → escape or damage
Claimant's fault and act of a stranger
These may initially look similar because another person's conduct causes the escape.
The identity of that person matters.
If the person is the claimant:
Consider claimant's fault.
If the person is an independent third party:
Consider act of a stranger.
This distinction can quickly point you towards the correct defence.
Do not confuse claimant's fault with every other tort defence
OCR separately requires students to study contributory negligence and volenti non fit injuria, as well as the land-specific defences.
For this lesson, the important point is that OCR's Rylands material expressly identifies damage caused through the claimant's fault as an available defence.
Do not automatically turn every piece of careless claimant behaviour into the same defence. Identify precisely which principle the facts support.
A complete defence checklist
After establishing the basic requirements from Rylands v Fletcher [Lesson 129. Rylands v Fletcher], ask:
Did a stranger cause the escape?
If yes, consider Perry v Kendricks Transport.
Could the defendant have anticipated or guarded against the interference?
Did an exceptional natural event cause the escape?
If yes, consider act of God and Nicholls v Marsland.
Did the claimant consent?
If yes, consider volenti non fit injuria and Peters v Prince of Wales Theatre.
Was the accumulation for the common benefit of the parties?
If yes, consider Dunne v North West Gas Board.
Did the claimant's own conduct cause the damage?
If yes, consider claimant's fault and Eastern & South African Telegraph v Cape Town Tramways.
Reach a conclusion.
State whether the defence is likely to succeed.
Explain which facts support or weaken it.
Defences do not replace the liability analysis
A common mistake is to spot a defence and discuss nothing else.
If an OCR question asks whether the claimant will succeed under Rylands v Fletcher, the safest structure is generally:
Stage 1: Establish the tort
Apply:
bringing onto and accumulation
likelihood of mischief
extraordinary and unusual use
escape
reasonably foreseeable actionable damage.
Stage 2: Apply any defence raised by the facts
For example:
The claimant appears to establish the requirements of Rylands v Fletcher. However, the escape was caused by an independent third party, so the defendant may rely on the act of a stranger defence.
Stage 3: Reach the final conclusion
The final answer must take the defence into account:
Although a prima facie claim exists, the defendant is unlikely to be liable if the act of a stranger defence succeeds.
This structure prevents the strange result of saying both:
"The defendant is liable."
and later:
"The defendant has a complete defence."
Worked application: act of a stranger
Consider:
Nadia operates a workshop. She stores a large quantity of industrial liquid in a tank outside the workshop. The requirements of Rylands v Fletcher have already been established. One night, three people enter the yard and deliberately damage the tank, causing the liquid to escape onto neighbouring land. Nadia knows that people have entered the yard several times in the previous month, but she has taken no steps to secure it.
Step 1: Identify the defence
The immediate cause of the escape is the conduct of independent third parties.
This raises act of a stranger.
Step 2: State the authority
Perry v Kendricks Transport is the relevant authority.
Step 3: Apply control
There is no indication that the three people are under Nadia's control.
This supports the defence.
Step 4: Apply anticipation and precautions
However, Nadia already knows that people have repeatedly entered the yard.
This suggests that further interference may have been foreseeable in a practical sense and that she may have been able to guard against it by securing the site.
OCR's 2025 material shows that precisely this type of factual issue can determine whether the defence succeeds.
Conclusion
Nadia can raise act of a stranger, but there is a strong argument that it will fail because previous incidents meant she could have anticipated and guarded against the interference.
A different conclusion could still receive credit if it were supported convincingly from the facts.
Worked application: act of God
Consider:
An actionable claim under Rylands v Fletcher has been established against Omar. A severe natural event causes the stored substance to escape from his land. There is no evidence that another person interfered with it.
The facts point towards act of God, not act of a stranger.
The answer should:
identify the natural event as the cause of the escape
explain the act of God defence
use Nicholls v Marsland
decide whether the facts support the defence.
If the defence succeeds, Omar avoids liability despite the basic Rylands requirements otherwise being present.
Worked application: claimant's fault
Consider:
Maya knows that her neighbour keeps a large tank beside the boundary. She enters the neighbour's property without permission and opens its outlet valve. Liquid flows through the boundary and damages Maya's own garden.
Assuming the basic Rylands requirements are otherwise satisfied, the defendant should consider damage caused through the claimant's fault.
Maya's own act has caused the escape and resulting damage.
Eastern & South African Telegraph v Cape Town Tramways is the authority identified by OCR.
This provides a strong argument that the defendant should not remain liable for the damage Maya herself caused.
Reaching supported conclusions
OCR problem questions reward legal reasoning, not merely the final word "liable" or "not liable".
A supported conclusion contains three parts:
Rule + decisive fact + outcome
For example:
Under Perry v Kendricks Transport, an act of a stranger may provide a defence where the escape is caused by a third party outside the defendant's control. Here, however, repeated earlier interference meant the defendant could arguably have guarded against another incident. The defence is therefore unlikely to succeed.
Compare that with:
The act of a stranger defence fails.
The second statement gives the conclusion but almost none of the reasoning needed for strong AO2.
Defences can produce more than one reasonable outcome
The 2025 OCR examination is especially important here.
OCR expressly accepted different conclusions depending on how candidates interpreted the facts surrounding the act of a stranger defence.
This means you should not force an artificial certainty where the scenario is ambiguous.
Useful language includes:
On balance...
The stronger argument is...
The defence is likely to succeed because...
However, it could be argued that...
If the court considers that the defendant could have guarded against the interference, the defence would be unlikely to succeed.
The next lesson, comparing the land-based torts [Lesson 131. Comparing torts connected to land], brings together the requirements and defences of private nuisance and Rylands v Fletcher.
Key Words 🔑
Key word | Student-friendly definition | How it may be used in an exam |
Act of a stranger | A defence where an independent person outside the defendant's control causes the escape, subject to whether the event could have been anticipated or guarded against. | Apply Perry v Kendricks Transport to third-party interference. |
Act of God | A defence where the escape is caused by an exceptional natural event. | Identify natural events capable of raising Nicholls v Marsland. |
Volenti non fit injuria | A defence based on the claimant's consent to the relevant risk or situation. | Apply Peters v Prince of Wales Theatre where the facts show consent. |
Common benefit | A defence associated with an accumulation maintained for the shared benefit of the parties. | Apply Dunne v North West Gas Board where the facts indicate common benefit. |
Claimant's fault | A defence where the claimant's own conduct causes the damaging event. | Apply Eastern & South African Telegraph v Cape Town Tramways where the claimant causes the escape or damage. |
Hints from the Examiner Reports 💡
Examiner hint: Explain the defence rather than merely naming it. OCR's 2025 report found that stronger responses explained both the elements of Rylands v Fletcher and the act of a stranger defence, while weaker candidates tended simply to state legal rules.
Examiner hint: Link the defence directly to the scenario. Successful 2025 candidates connected the third-party interference to the act of a stranger rule and then considered whether the defendant could have anticipated or guarded against it.
Examiner hint: A reasoned alternative conclusion can still be successful. OCR's 2025 mark scheme accepted either that the defendant had a valid act of a stranger defence or that it failed because the defendant might reasonably have guarded against the interference, provided the conclusion was supported.
Examiner hint: Do not use material outside the specification simply because you know it. OCR specifically reported that less successful 2025 responses sometimes included detail outside the specification.
Examiner hint: Do not neglect the basic Rylands requirements when the question asks about overall liability. The defence is applied after establishing the underlying claim, unless the question specifically tells you that liability has already been established.
Examiner hint: Be selective. OCR's general examination guidance emphasises explaining relevant principles and linking them to facts rather than producing large quantities of unrelated legal material.
Common Mistakes ⚠️
Mistake: Assuming any third-party act automatically provides a defence
Why this is incorrect: The 2025 OCR materials show that the act of a stranger defence requires more analysis. A third party outside the defendant's control may cause the escape, but the court may also need to consider whether the defendant could have anticipated or guarded against the interference.
How to improve: Apply both sides of the argument before reaching a conclusion.
Mistake: Spotting a defence but not explaining the underlying Rylands claim
Why this is incorrect: If the question asks whether the claimant will succeed overall, AO1 and AO2 may require the elements of Rylands v Fletcher as well as the defence.
How to improve: Establish prima facie liability first, then apply the defence.
Mistake: Confusing act of God with act of a stranger
Why this is incorrect: They arise from different causes.
How to improve: Ask what caused the escape. A natural event points towards act of God. Independent human interference points towards act of a stranger.
Mistake: Treating knowledge as consent
Why this is incorrect: A claimant being aware of the accumulated thing does not automatically establish volenti.
How to improve: Look for facts demonstrating consent before relying on Peters v Prince of Wales Theatre.
Mistake: Confusing common benefit with general public benefit
Why this is incorrect: OCR identifies common benefit as the relevant Rylands defence.
How to improve: Look for facts showing that the arrangement benefits the parties concerned rather than simply providing some wider social benefit.
Mistake: Missing claimant's fault
Why this is incorrect: If the claimant's own conduct causes the escape or damage, OCR identifies this as a specific available defence.
How to improve: Trace the factual chain carefully. Ask who actually caused the thing to escape.
Mistake: Giving an unsupported conclusion
Why this is incorrect: Simply writing "the defence succeeds" does not demonstrate application.
How to improve: Use a decisive fact in every conclusion:
Because the earlier incidents meant D could have guarded against interference, the act of a stranger defence is unlikely to succeed.
Exam-Style Questions ✍️
Question 1
Name the defence that may apply where an independent third party causes an escape under Rylands v Fletcher. [1 mark]
Question 2
Explain the act of a stranger defence. Refer to relevant legal authority. [4 marks]
Question 3
Explain the act of God defence in Rylands v Fletcher. Refer to relevant legal authority. [4 marks]
Question 4
Explain two of the following defences:
volenti non fit injuria
common benefit
damage caused through the claimant's fault.
[6 marks]
Question 5
An actionable claim under Rylands v Fletcher has been established against Kieran. An unknown person enters Kieran's securely fenced land during the night and deliberately opens the valve on a storage tank. There have been no previous incidents of trespass or interference.
Explain whether Kieran may have a defence. [6 marks]
Question 6
An actionable claim under Rylands v Fletcher has been established against Priya. During an exceptional natural storm, the accumulated substance escapes from Priya's land and damages neighbouring property.
Explain the defence Priya may rely upon. [6 marks]
Question 7
An actionable Rylands v Fletcher claim has been established against Tarek. The claimant, Chloe, entered Tarek's land and deliberately damaged the container in which the relevant substance was stored. The substance escaped onto Chloe's neighbouring land and damaged her property.
Advise Tarek whether a defence is available. [8 marks]
Question 8
Mina stores a large quantity of chemical liquid on land next to Leon's garden. Assume that all the requirements of Rylands v Fletcher are satisfied.
Several local teenagers have entered Mina's land during the previous month and interfered with equipment. Mina knows this but leaves the chemical container outside and takes no additional security precautions. One night a teenager deliberately knocks the container over. The liquid escapes onto Leon's garden and destroys his plants.
Advise whether Mina can successfully rely on the act of a stranger defence. [10 marks]
Question 9
Assume in each situation that the requirements of Rylands v Fletcher have been established.
A. An independent trespasser breaks through a secure fence and deliberately damages a storage tank. There has never previously been any trespass or interference.
B. An exceptional natural event causes an accumulated substance to escape.
C. The claimant personally damages the defendant's container and causes the substance to escape.
D. The accumulation exists as part of an arrangement maintained for the benefit of both claimant and defendant.
Advise each defendant whether a defence may be available. [20 marks]
Indicative answers and mark scheme
Question 1
Award 1 mark for:
Act of a stranger.
Question 2
Award up to 4 marks for explaining that:
an independent third party causes the escape
the person is outside the defendant's control
Perry v Kendricks Transport is relevant authority
the court may consider whether the defendant could have anticipated or guarded against the interference.
Question 3
Award up to 4 marks for:
identifying act of God
explaining that the escape results from an exceptional natural event
appropriate reference to Nicholls v Marsland
explaining that a successful defence prevents the defendant from remaining liable under Rylands v Fletcher.
Question 4
Award up to 3 marks for each accurately explained defence, to a maximum of 6.
Relevant content includes:
Volenti non fit injuria
concerns the claimant's consent
Peters v Prince of Wales Theatre.
Common benefit
applies where the relevant arrangement or accumulation exists for the common benefit of the parties
Dunne v North West Gas Board.
Claimant's fault
the claimant's own conduct causes the damaging event
Eastern & South African Telegraph v Cape Town Tramways.
Question 5
A strong answer should explain that:
the escape is caused by an independent third party
this raises act of a stranger
Perry v Kendricks Transport is relevant
the stranger is outside Kieran's control
Kieran had secured the land
there had been no previous interference suggesting the event should have been anticipated
the facts therefore strongly support the defence.
Conclusion: Kieran is likely to avoid liability through the act of a stranger defence.
Question 6
A strong answer should explain that:
the relevant defence is act of God
Nicholls v Marsland is the authority identified by OCR
the escape has been caused by an exceptional natural event
the facts therefore support the defence.
Conclusion: Priya has a strong argument that the defence applies.
Question 7
A strong answer should explain that:
Chloe herself deliberately damaged the container
her conduct caused the escape
this raises damage caused through the claimant's fault
Eastern & South African Telegraph v Cape Town Tramways is relevant
Tarek can argue that he should not be liable for damage caused through Chloe's own conduct.
Conclusion: Tarek has a strong defence based on claimant's fault.
Question 8
A strong answer should consider both sides.
Defence raised
A teenager, who is an independent third party, causes the chemical to escape.
The facts therefore raise act of a stranger, supported by Perry v Kendricks Transport.
Control
There is no indication that Mina controls the teenager. This supports the defence.
Anticipation
However, several teenagers have already entered Mina's property and interfered with equipment.
Mina knows about these previous incidents.
This substantially weakens the defence because further third-party interference may have been something she could anticipate.
Guarding against the interference
Mina nevertheless leaves the chemical container outside and takes no additional precautions.
This supports an argument that she could have guarded against the interference.
OCR's 2025 material demonstrates that the success of this defence can depend on precisely this question.
Conclusion
Although the immediate cause of the escape is the act of a stranger, Mina is unlikely to establish the defence successfully because the previous incidents suggest that she could have anticipated and guarded against further interference.
A contrary conclusion could be supported if the facts were interpreted differently, but it would need clear reasoning.
Question 9
A high-level response should apply the correct defence separately to each scenario.
A. Independent trespasser
The facts raise act of a stranger.
Under Perry v Kendricks Transport, a defendant may avoid liability where an independent third party outside their control causes the escape.
The secure fence and absence of any previous interference suggest the defendant had little reason to anticipate or guard further against what happened.
Conclusion: The defence is likely to succeed.
B. Exceptional natural event
The relevant defence is act of God.
Nicholls v Marsland is the authority identified by OCR.
The natural event is stated to have caused the escape.
Conclusion: The defendant has a strong argument that act of God provides a defence.
C. Claimant damages the container
The relevant defence is damage caused through the claimant's fault.
The claimant's own deliberate conduct causes the escape.
Eastern & South African Telegraph v Cape Town Tramways is relevant.
Conclusion: The defendant has a strong defence.
D. Common benefit
The arrangement is expressly said to benefit both claimant and defendant.
This raises the defence of common benefit, supported by Dunne v North West Gas Board.
Conclusion: The facts support the availability of the common benefit defence.
Across all four situations, the strongest answers identify the correct defence from the factual trigger, explain the relevant principle and authority, apply the precise facts and then reach a supported conclusion.
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