Defences to Nuisance and Rylands v Fletcher | AQA A-Level Law
For Specification 7162
AQA A-Level Law | Free Revision Notes
Estimated study time: 45 minutes
Even where a claimant establishes the requirements of private nuisance or Rylands v Fletcher, the defendant may still avoid liability if an appropriate defence applies. These Defences to nuisance and Rylands v Fletcher A-Level Law revision notes explain the principal defences associated with each tort, including prescription and statutory authority in private nuisance, and act of God and an unforeseen act of a stranger under Rylands v Fletcher. The lesson develops private nuisance [Lesson 107. Private nuisance] and the rule in Rylands v Fletcher [Lesson 108. The rule in Rylands v Fletcher].
Learning Objectives 🎯
By the end of this revision page, you should be able to:
Explain the defences relevant to private nuisance.
Explain why coming to the nuisance is not a valid defence.
Explain prescription and statutory authority in private nuisance.
Explain the act of God defence under Rylands v Fletcher.
Explain the unforeseen act of a stranger defence under Rylands v Fletcher.
Apply the appropriate defence to factual scenarios and explain its effect upon liability.
Revision Notes 📚
When do defences become relevant?
A defence should normally be considered after the claimant has established the requirements of the tort.
For private nuisance, first establish the requirements covered in private nuisance [Lesson 107. Private nuisance].
For Rylands v Fletcher, first establish the requirements covered in the rule in Rylands v Fletcher [Lesson 108. The rule in Rylands v Fletcher].
The basic structure is:
Establish the claimant's cause of action.
Identify any defence raised by the facts.
Explain the requirements of that defence.
Apply those requirements precisely.
Decide whether the defence succeeds.
If no complete defence succeeds, consider the appropriate remedy.
A common examination mistake is to identify a possible defence but never explain why its requirements are or are not satisfied.
Defences to private nuisance
Private nuisance protects a claimant's interest in land against substantial interference with its ordinary use and enjoyment.
A defendant who would otherwise be liable may attempt to rely upon a defence.
The principal private nuisance defences to understand are:
prescription
statutory authority.
You should also remember an important non-defence:
Coming to the nuisance is not a defence.
Prescription
Prescription may provide a defence where the defendant has carried on the actionable nuisance for the required period without successful legal challenge.
The relevant period is 20 years.
The underlying idea is that, after the nuisance has continued openly as of right for the necessary period, the defendant may acquire a legal right to continue the activity.
The 20 years concerns the nuisance itself
Do not simply ask:
"Has the defendant carried out this activity for 20 years?"
The important issue is whether the activity has amounted to an actionable nuisance for 20 years.
This distinction matters.
Example
A workshop has operated for 30 years.
For its first 25 years it produces only moderate daytime noise which does not substantially interfere with neighbouring land.
Five years ago, the owner installs much louder machinery which runs late into the night and creates an actionable nuisance.
The defendant cannot simply argue:
"The workshop has been here for 30 years, therefore I have prescription."
The relevant nuisance has existed for only five years.
Prescription is more than long use
For a prescription argument to succeed, the defendant needs to establish the required period of actionable interference.
A strong examination answer therefore identifies:
what the nuisance is
when it became actionable
whether 20 years have passed.
Do not award the defendant the defence merely because an activity has a long history.
Worked prescription example
Luca owns a workshop.
For 23 years, Luca has operated the same machinery at the same level of noise. The noise has continuously and substantially interfered with the ordinary use of the neighbouring house throughout that period.
Mina buys the neighbouring house and brings a private nuisance claim.
If the facts establish that the same actionable nuisance has continued openly for more than 20 years, Luca may argue prescription.
The fact that Mina personally has only recently moved into the property does not determine the 20-year period. The focus is upon the length of the actionable nuisance.
Statutory authority
Statutory authority may provide a defence where legislation authorises the defendant's activity in circumstances where the nuisance is an inevitable consequence of carrying out the authorised activity.
The crucial word is statutory.
The authority must come from legislation.
A contract with a public body is not statutory authority
This was specifically highlighted in an AQA examiner report.
A defendant does not acquire statutory authority merely because:
a council gives them a contract
a public organisation pays for the work
the activity provides a public service.
A council awarding a commercial contract is not the same thing as Parliament authorising the nuisance through legislation.
Example
A local council hires a company to cut timber.
The timber cutting creates substantial noise affecting neighbouring land.
The company cannot simply argue:
"The council gave us the contract, so we have statutory authority."
A contract and statutory authority are legally different.
What must the defendant show?
A good statutory authority analysis should ask:
Is there legislation authorising the relevant activity?
What exactly does the legislation permit or require?
Is the nuisance an inevitable consequence of carrying out that statutory power?
If the activity could reasonably be carried out without creating the nuisance, the defence may be much harder to establish.
Worked statutory authority example
Suppose an Act of Parliament specifically authorises the construction and operation of particular infrastructure at a named location.
The authorised activity inevitably produces a particular level of interference with neighbouring land.
If the defendant acts within the statutory authority, there may be a defence to private nuisance.
Now change the facts.
A local authority merely awards the defendant an ordinary commercial contract to operate noisy machinery.
That fact alone does not amount to statutory authority.
Coming to the nuisance is not a defence
A defendant may argue:
"I was carrying out this activity before the claimant moved next door."
This is called coming to the nuisance.
It is not a defence.
The fact that a claimant acquires or moves into property after the defendant's activity has already begun does not automatically prevent a private nuisance claim.
AQA examiner reports and mark schemes repeatedly emphasise this point.
Why coming to the nuisance must not be confused with prescription
These rules are easy to muddle.
Coming to the nuisance | Prescription |
Claimant moves to the area after defendant's activity has begun | Actionable nuisance has continued for the required 20-year period |
Not a defence | May be a defence |
Length of claimant's personal occupation is not decisive | Duration of the actionable nuisance is central |
Defendant cannot simply say "I was here first" | Defendant must satisfy the requirements of prescription |
Example
A nightclub has generated excessive noise for five years.
Aisha buys the neighbouring house this year.
The nightclub cannot defeat her claim simply because:
"The noise existed before Aisha arrived."
That is merely coming to the nuisance.
The 20-year requirement for prescription has not been satisfied.
Consent and private nuisance
The general defence of consent [Lesson 112. Consent] should be kept distinct from the private nuisance-specific defences.
If the claimant genuinely knows about and freely accepts a relevant risk, consent may potentially arise where the facts support it.
However, do not confuse:
moving next to an existing activity
with:
legally consenting to an actionable nuisance.
Moving into an area where the activity already exists does not automatically prove valid consent.
Defences to Rylands v Fletcher
The rule in Rylands v Fletcher is a form of strict liability.
However, strict liability does not mean unlimited liability.
A defendant may avoid liability where an appropriate defence explains why the escape should not legally be attributed to them.
The two particularly important defences appearing repeatedly in AQA assessment materials are:
act of God
unforeseen act of a stranger.
Act of God
An act of God is an extraordinary natural event which is so exceptional that it could not reasonably have been foreseen and guarded against.
The defence focuses upon a natural event rather than human intervention.
The defendant's argument is essentially:
The escape was caused by an extraordinary force of nature which I could not reasonably have anticipated or prevented.
Nichols v Marsland
Nichols v Marsland is the authority identified in AQA materials in connection with the act of God defence.
For examination purposes, use it to support the principle that an extraordinary natural event may prevent liability under Rylands v Fletcher.
An ordinary natural event is not necessarily an act of God
The defence requires more than proof that:
it rained
there was wind
there was a storm
some other natural event occurred.
The event must be sufficiently exceptional and unforeseeable.
Example
A defendant stores a dangerous substance in conditions suitable for the normal weather in that area.
An entirely unprecedented natural event then causes the substance to escape.
The defendant may have an argument based on act of God.
By contrast, if heavy rain or storms are common and the escape could have been prevented by ordinary precautions, the defence is much weaker.
AQA application: the very bad storm
AQA has previously tested a scenario in which a very bad storm carried accumulated material from the defendant's land.
Students were expected to consider whether the storm amounted to an act of God.
The correct approach is not merely:
"There was a storm, so the defence succeeds."
Instead ask:
How unusual was the storm?
Was it reasonably foreseeable?
Could precautions have guarded against its effects?
Worked act of God example
Priya stores a large quantity of a dangerous substance on her land in circumstances satisfying the requirements of Rylands v Fletcher.
An extraordinary storm of unprecedented severity causes the substance to escape onto Ravi's property.
Priya may argue:
The escape was caused by a natural event.
The event was extraordinary.
It could not reasonably have been anticipated.
It could not reasonably have been guarded against.
If established, the act of God defence may defeat Ravi's claim.
What if the defendant could have guarded against the event?
The defence becomes much weaker if the defendant knew or should reasonably have anticipated the natural risk.
For example:
serious flooding occurs regularly
weather warnings make the event foreseeable
simple precautions could have contained the accumulated substance.
In such circumstances, the defendant cannot merely label the event an "act of God".
The key issue is whether it was truly unforeseeable and unavoidable.
Act of a stranger
An act of a stranger may provide a defence where the escape results from an unforeseeable act of a third party over whom the defendant has no relevant control.
The stranger's intervention breaks the basis for imposing strict liability upon the defendant.
Perry v Kendricks Transport
Perry v Kendricks Transport is an authority identified by AQA for the act of a stranger defence.
For examination purposes, use it to support the principle that an unforeseeable act by an independent third party can provide a defence.
The stranger must genuinely be outside the defendant's control
Ask:
Who caused the escape?
What relationship did that person have with the defendant?
Could the defendant control their behaviour?
Was their intervention reasonably foreseeable?
The strongest case for the defence is where an independent third party unexpectedly interferes with the dangerous accumulation.
The act must be unforeseen
AQA's 2025 examiner report emphasised the importance of describing this accurately as an unforeseen act of a stranger.
The fact that another person physically causes the escape does not automatically establish the defence.
If the stranger's intervention was reasonably foreseeable, the defendant may still be liable.
Worked stranger example
Lara stores a large quantity of petrol on her land.
An unknown intruder secretly enters during the night and deliberately damages the storage tank, causing petrol to escape onto neighbouring land.
If:
Lara had no reason to anticipate the intrusion
the intruder was entirely independent of her
the deliberate damage was unforeseeable
Lara may be able to rely upon an unforeseen act of a stranger.
Foreseeable strangers
Now change the facts.
Lara knows that teenagers regularly enter the property.
They have previously interfered with equipment and caused minor damage.
She nevertheless leaves the petrol storage easily accessible.
If a teenager damages the tank, the defence becomes much more difficult.
Why?
Because the intervention of a third party may no longer be genuinely unforeseeable.
The court may conclude that Lara should reasonably have anticipated the possibility of interference.
AQA's 2025 approach
AQA's 2025 examination involved teenagers who were known to enter premises and race go-karts, followed by one of them setting fire to stored petrol.
The key question was not simply:
"Was a stranger involved?"
The better analysis asked:
Although entry by teenagers was known, was this particular destructive act nevertheless unforeseeable?
This illustrates why the defence must be applied, not merely named.
Stranger and defendant negligence
The defence may also fail where the defendant has acted negligently in relation to the third party's interference.
AQA's 2023 mark scheme expressly recognised that the defence may be unavailable where the defendant failed to deal appropriately with damage caused by an intruder.
Example
An intruder damages an oil tank but no escape initially occurs.
The defendant discovers the damage and does nothing.
Several days later, the tank fails and oil escapes.
The defendant may struggle to argue that the escape was solely the unforeseen act of a stranger because their own failure to respond has contributed to what happened.
2023 AQA application
AQA's 2023 assessment required students to consider vandalism by an intruder.
The strongest answers did not merely say:
"There was an intruder, so act of a stranger applies."
They considered whether:
the intruder actually caused the damage
the defendant's own failure to repair or respond prevented reliance on the defence.
This is a useful model for all defence questions.
Act of God and act of a stranger compared
Act of God | Act of a stranger |
Escape caused by extraordinary natural forces | Escape caused by an independent third party |
Natural event must be exceptional and unforeseeable | Third-party intervention must be unforeseeable |
Event must not reasonably be capable of being guarded against | Defendant must not reasonably have been expected to prevent the interference |
Nichols v Marsland | Perry v Kendricks Transport |
Focus on nature | Focus on human intervention |
A simple memory aid is:
Nature = act of God
Unexpected outsider = act of stranger
Statutory authority and Rylands v Fletcher
Where legislation expressly authorises an activity, statutory authority may also become relevant to liability under Rylands v Fletcher.
As with private nuisance, do not confuse actual statutory authority with:
a commercial contract
permission from a private person
an activity merely being useful to the public.
The precise legislation and scope of the authority matter.
For examination purposes, however, AQA's recent Rylands v Fletcher scenarios have focused particularly heavily on act of God and unforeseen act of a stranger.
Consent and contributory negligence
The general defences studied in the previous lessons should remain separate from the tort-specific defences.
Consent
Under consent [Lesson 112. Consent], the claimant must actually know of and freely accept the relevant risk.
Contributory negligence
Under contributory negligence [Lesson 111. Contributory negligence], the claimant's failure to take reasonable care for their own safety may reduce damages.
If a scenario clearly raises either defence, apply it using its own requirements.
Do not try to convert every claimant action into a special Rylands v Fletcher defence.
Strict liability and defences
The existence of these defences helps explain what strict liability really means.
Under Rylands v Fletcher, the claimant does not have to prove ordinary negligence.
However, the defendant is not automatically responsible for every escape.
For example, liability may be excluded where:
extraordinary natural forces caused an unforeseeable escape
an unforeseeable independent stranger caused the escape.
The law therefore imposes strict liability only within controlled limits.
Fault can still matter indirectly
The defences also show how ideas resembling fault can affect a strict liability tort.
For example:
if the defendant could reasonably foresee a stranger interfering, the stranger defence may fail
if the defendant could reasonably guard against a natural event, act of God may fail
if the defendant discovers third-party damage but negligently does nothing, they may be unable to rely upon the stranger's original act.
This does not transform Rylands v Fletcher into negligence.
Instead, it limits the circumstances in which strict liability is imposed.
How to choose the correct defence
Private nuisance scenario
Ask:
Has the actionable nuisance continued for 20 years?
→ consider prescription
Does legislation authorise the activity and make the nuisance inevitable?
→ consider statutory authority
Is the defendant merely saying the claimant moved there after the activity began?
→ coming to the nuisance is not a defence
Rylands v Fletcher scenario
Ask:
Was the escape caused by an extraordinary natural event?
→ consider act of God
Was the escape caused by an unexpected independent third party?
→ consider act of a stranger
Was the third party's interference foreseeable?
→ the stranger defence may fail
Could the defendant reasonably have guarded against the natural event?
→ act of God may fail
This identification stage can save considerable time in an examination.
A complete private nuisance defence structure
Step 1: Establish private nuisance
Do not spend the whole answer on defences if the underlying tort is uncertain.
Step 2: Identify the defence
Is the defendant arguing:
prescription
statutory authority?
Step 3: State its requirements
Avoid simply naming the defence.
Step 4: Apply the facts
For prescription:
how long has the actionable nuisance existed?
For statutory authority:
what legislation authorises the activity?
is the nuisance inevitable?
Step 5: Reject false defences
If the defendant argues that the claimant "came to the nuisance", state that this is not a defence.
Step 6: Conclude
Explain whether liability remains.
If it does, move to mitigation and injunctions [Lesson 115. Mitigation and injunctions] where an injunction is relevant.
A complete Rylands v Fletcher defence structure
Step 1: Establish the rule
Confirm that the claimant can establish:
legal interest
accumulation
dangerous thing
non-natural use
escape
foreseeable damage.
Step 2: Identify what caused the escape
Was it:
nature
a third party
the defendant's own conduct?
Step 3: Apply the appropriate defence
Nature: act of God.
Third party: unforeseen act of a stranger.
Step 4: Test foreseeability
Could the defendant reasonably have anticipated what happened?
Step 5: Test preventability
Could reasonable precautions have guarded against the cause of escape?
Step 6: Consider the defendant's own conduct
Did the defendant know of the danger or third-party interference and fail to respond?
Step 7: Reach a conclusion
If a complete defence succeeds, the defendant avoids liability.
If it fails, strict liability may remain and compensatory damages [Lesson 114. Compensatory damages] may be available.
Worked application: private nuisance
Maya owns a cottage.
Next door, Noah operates machinery which has created a substantial noise nuisance for the last six years.
Noah says:
"The machinery was already operating when Maya bought the cottage three years ago, so she cannot complain."
This argument fails.
Maya has come to the nuisance, but that is not a defence.
Noah also cannot establish prescription because the actionable nuisance has continued for only six years rather than the required 20 years.
Subject to the other requirements of private nuisance, Maya's claim may therefore proceed.
Worked application: statutory authority
Parliament passes legislation specifically requiring particular machinery to operate at a stated location. The authorised activity cannot be carried out without creating a particular interference with nearby land.
The operator may argue statutory authority.
The analysis should consider:
whether the activity is genuinely authorised by legislation
whether the defendant remains within that statutory authority
whether the nuisance is an inevitable consequence of performing the authorised activity.
Do not assume that a public body merely approving or purchasing the service creates statutory authority.
Worked application: act of God
Omar accumulates a dangerous substance on his land in circumstances satisfying Rylands v Fletcher.
An unprecedented natural event of extraordinary severity causes the storage system to fail and the substance escapes onto Priya's land.
If Omar could neither reasonably foresee the event nor guard against it, he may rely on act of God.
If similar events occur regularly and precautions were available, the defence is less likely to succeed.
Worked application: act of stranger
Ruth stores oil on her land.
An unknown vandal unexpectedly enters at night and damages the storage tank. Oil escapes onto Salim's neighbouring land.
Ruth has never previously experienced trespassing and has no reason to anticipate deliberate interference.
The vandal is an independent third party and the conduct appears unforeseeable.
Ruth therefore has a strong argument based on act of a stranger.
Change the facts
Suppose instead:
trespassers enter every weekend
Ruth knows they regularly damage equipment
Ruth takes no additional precautions.
The defence becomes significantly weaker because further interference may have been reasonably foreseeable.
Defences and remedies
A complete defence prevents liability for the relevant claim.
If no complete defence succeeds, the claimant may move to remedies.
For private nuisance, possible remedies include:
damages
an injunction.
For Rylands v Fletcher, compensatory damages may be available for relevant property loss.
These are developed in:
compensatory damages [Lesson 114. Compensatory damages]
mitigation and injunctions [Lesson 115. Mitigation and injunctions].
When answering a full problem, keep the sequence clear:
liability → defence → remedy
This structure is particularly useful for synoptic tort problems [Lesson 116. Synoptic tort problems].
Key Words 🔑
Key word | Student-friendly definition | How it may be used in an exam |
Prescription | A private nuisance defence based on the actionable nuisance having continued for the required 20-year period. | Check how long the nuisance itself, rather than merely the defendant's activity, has been actionable. |
Statutory authority | A defence where legislation authorises an activity and the nuisance is an inevitable consequence of carrying out that authority. | Distinguish genuine legislative authority from an ordinary contract or permission. |
Act of God | An extraordinary natural event which could not reasonably have been foreseen or guarded against. | Explain why an exceptional natural event may defeat a Rylands v Fletcher claim. |
Act of a stranger | An unforeseeable act of an independent third party which causes the escape. | Analyse whether third-party interference was genuinely outside the defendant's control and reasonably unforeseeable. |
Coming to the nuisance | The claimant moves to the affected property after the defendant's activity has already begun. | Recognise that this is not a defence to private nuisance. |
Hints from the Examiner Reports 💡
Examiner hint: Do not call coming to the nuisance a defence. AQA has repeatedly identified this as incorrect, including in the 2025 assessment.
Examiner hint: Do not invent statutory authority from the facts. The 2022 examiner report specifically criticised students who argued that a local council had given statutory authority merely by awarding the defendant a commercial contract.
Examiner hint: When using act of God, explain the requirements. The fact that a storm occurred does not automatically establish the defence. Consider whether the natural event was extraordinary, unforeseeable and incapable of being guarded against.
Examiner hint: Do not simply write "act of a stranger applies". In 2023, stronger answers considered whether an intruder actually caused the escape and whether the defendant's own failure to respond to the damage prevented reliance upon the defence.
Examiner hint: AQA's 2025 report emphasised that the relevant Rylands v Fletcher defence is an unforeseen act of a stranger. Even if the defendant knows people sometimes enter the land, consider whether the particular destructive action was foreseeable.
Examiner hint: Keep the underlying Rylands v Fletcher requirements separate from the defence. Establish accumulation, dangerous thing, non-natural use, escape and foreseeable damage before asking whether act of God or act of a stranger defeats liability.
Examiner hint: Do not discuss several defences merely because you remember them. Select the defence actually raised by the scenario and apply it carefully.
Common Mistakes ⚠️
Mistake: Treating coming to the nuisance as a defence
Why this is incorrect: A claimant does not lose their right to complain merely because the defendant's activity began before they acquired or occupied the neighbouring property.
How to improve: State expressly that coming to the nuisance is not a defence. Consider prescription separately if the facts mention a long period of actionable nuisance.
Mistake: Starting the 20-year prescription period when the activity began
Why this is incorrect: The relevant question is how long the actionable nuisance has existed.
How to improve: Identify when the interference became sufficiently substantial to constitute private nuisance and count from that point.
Mistake: Assuming a council contract creates statutory authority
Why this is incorrect: Statutory authority must come from legislation.
How to improve: Identify the statute or statutory power relied upon and ask whether the nuisance is an inevitable consequence of exercising it.
Mistake: Treating any storm as an act of God
Why this is incorrect: Normal or foreseeable natural conditions do not automatically provide the defence.
How to improve: Explain why the event was extraordinary, unforeseeable and incapable of being guarded against.
Mistake: Assuming any third-party involvement proves act of a stranger
Why this is incorrect: The stranger's intervention must be sufficiently independent and unforeseeable.
How to improve: Consider previous trespassing, previous interference, the defendant's knowledge and the precautions reasonably available.
Mistake: Ignoring the defendant's conduct after a stranger intervenes
Why this is incorrect: If the defendant learns about damage caused by a stranger and fails to deal with it, their own conduct may contribute to the eventual escape.
How to improve: Trace the chain of events and ask what the defendant knew before the escape occurred.
Mistake: Forgetting that Rylands v Fletcher is strict liability
Why this is incorrect: Act of God and act of stranger operate as defences to a tort which does not ordinarily require proof of negligence.
How to improve: Do not turn the whole claim into a negligence analysis. Apply the Rylands requirements first and the specific defence second.
Mistake: Confusing consent with coming to the nuisance
Why this is incorrect: Moving next to an existing activity does not automatically amount to freely accepting an actionable interference.
How to improve: Apply the actual requirements of consent [Lesson 112. Consent] separately if the facts genuinely raise it.
Exam-Style Questions ✍️
Question 1
Which one of the following is not a defence to private nuisance?
A. Prescription
B. Statutory authority
C. Coming to the nuisance
D. A valid applicable defence provided by law
[1 mark]
Question 2
Explain what is meant by prescription as a defence to private nuisance.
[2 marks]
Question 3
Explain the difference between the act of God and act of a stranger defences under Rylands v Fletcher.
[4 marks]
Question 4
A factory has operated for 30 years. It produced little noise for its first 25 years. Five years ago, new machinery was installed and has since created a substantial private nuisance.
The factory argues that it has acquired a right by prescription because it has operated for 30 years.
Explain why this argument may fail.
[5 marks]
Question 5
A timber company causes a private nuisance while carrying out work under a contract awarded by a local council.
The company argues that it has a defence of statutory authority because the council commissioned the work.
Explain why this argument is insufficient.
[5 marks]
Question 6
Nadia accumulates a dangerous substance on her land in circumstances satisfying the rule in Rylands v Fletcher.
An exceptionally severe and unprecedented natural event causes the substance to escape onto Omar's neighbouring land. No reasonable precaution could have prevented the escape.
Advise Nadia as to whether a defence may be available.
[10 marks]
Question 7
Priya stores a large quantity of oil on her land.
She knows that teenagers regularly enter the premises to ride bicycles but they have never previously interfered with the oil storage. One night, a teenager deliberately damages the oil tank and oil escapes onto Ravi's land.
Analyse whether Priya may rely upon the defence of an unforeseen act of a stranger.
[10 marks]
Question 8
Analyse the defences applicable to private nuisance and the rule in Rylands v Fletcher, including circumstances in which apparent defences will fail.
[15 marks]
Mark Scheme
Question 1
Answer: C. [1 mark]
Coming to the nuisance is not a defence. A claimant does not lose their private nuisance rights merely because the defendant's activity was already occurring when the claimant arrived.
Question 2
Award up to 2 marks:
1 mark: Prescription may arise where an actionable private nuisance has continued for the required period of 20 years.
1 mark: The period concerns the actionable nuisance itself, rather than simply the length of time the defendant has carried on some activity on the land.
Question 3
Award up to 4 marks:
Act of God concerns an extraordinary natural event.
The event must be sufficiently unforeseeable and incapable of reasonably being guarded against.
Act of a stranger concerns intervention by an independent third party.
The third party's conduct must be sufficiently unforeseeable and outside the defendant's control.
Credit relevant reference to Nichols v Marsland and Perry v Kendricks Transport.
Question 4
Award up to 5 marks.
Indicative content:
Prescription concerns the period for which the actionable nuisance has existed.
The factory itself has operated for 30 years.
However, the original activity did not amount to a substantial private nuisance.
The actionable interference began only when the new machinery was installed.
That occurred five years ago.
The required 20-year period has therefore not been established.
Prescription is unlikely to provide a defence.
Question 5
Award up to 5 marks.
Indicative content:
Statutory authority must arise from legislation or an appropriate statutory power.
A commercial contract from a local authority does not itself amount to statutory authority.
The company must identify a statutory basis authorising the activity.
It must also establish that the nuisance is an inevitable consequence of carrying out that statutory authority.
The council merely commissioning the work is therefore insufficient.
AQA examiner guidance specifically identifies this distinction.
Question 6
Award up to 10 marks for knowledge, application and reasoned legal argument.
Indicative content:
Nadia's liability under Rylands v Fletcher is assumed to have been established before the defence is considered.
The possible defence is act of God.
This concerns an extraordinary natural event causing the escape.
The event is described as exceptionally severe and unprecedented.
This supports the argument that it was not reasonably foreseeable.
The facts also state that no reasonable precaution could have prevented the escape.
These facts strongly support the defence.
Nichols v Marsland may be used as supporting authority.
If the court accepts that the event was truly extraordinary, unforeseeable and unavoidable, the defence may completely defeat Omar's claim under Rylands v Fletcher.
If the event should reasonably have been anticipated, the defence would fail.
Question 7
Award up to 10 marks.
Indicative content:
The possible defence is an unforeseen act of a stranger.
The teenager is a third party and is not acting on Priya's behalf.
The immediate cause of the escape is the deliberate damage to the oil tank.
Priya does know that teenagers regularly enter the premises.
This means some third-party presence is foreseeable.
However, their known activity is riding bicycles and they have never previously interfered with the oil.
There is therefore an argument that deliberately damaging the tank remained unforeseeable.
Against Priya, the court could consider whether repeated known trespass meant she should have taken steps to secure the dangerous oil storage.
The question is therefore not merely whether the teenager was a stranger but whether the particular intervention was reasonably foreseeable.
Perry v Kendricks Transport may support the defence.
A reasoned conclusion either way should be credited.
Question 8
Award up to 15 marks according to the quality of legal knowledge, explanation and analysis.
A strong response may include:
recognition that defences are considered after the requirements of the underlying tort have been established
prescription as a private nuisance defence
the requirement for 20 years of actionable nuisance
distinction between the duration of the activity and the duration of the nuisance
statutory authority
the need for genuine legislative authority
the requirement that the nuisance is an inevitable consequence of exercising that authority
recognition that an ordinary council or commercial contract does not itself create statutory authority
recognition that coming to the nuisance is not a defence
distinction between coming to the nuisance and prescription
recognition that moving near an existing nuisance is not automatically consent
Rylands v Fletcher as a form of strict liability
the act of God defence
an extraordinary, unforeseeable natural event which could not reasonably be guarded against
possible use of Nichols v Marsland
the unforeseen act of a stranger defence
the requirement for independent third-party intervention
the relevance of foreseeability
possible use of Perry v Kendricks Transport
recognition that known recurring trespass or interference may weaken the stranger defence
recognition that the defendant's own failure to respond to third-party damage may prevent reliance upon the defence
distinction from the general defences of contributory negligence [Lesson 111. Contributory negligence] and consent [Lesson 112. Consent]
recognition that a successful complete defence prevents liability
where no defence succeeds, the claimant may proceed to remedies including compensatory damages [Lesson 114. Compensatory damages] or, for private nuisance, an injunction considered in mitigation and injunctions [Lesson 115. Mitigation and injunctions]
a substantiated conclusion showing that each defence must be specifically explained and applied rather than merely identified.
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