Defences to negligence - Necessity

Learning Outcomes

This article explains the defence of necessity in the context of negligence claims. After studying this material, you should be able to identify the core requirements for the defence of necessity, distinguish it from other related defences, and apply the relevant legal principles to factual scenarios typical of the SQE1 assessment. You will understand the circumstances in which actions, otherwise considered negligent, may be excused due to the need to prevent greater harm.

SQE1 Syllabus

For SQE1, you are required to understand the fundamental principles of defences to negligence, including necessity. You should be able to:

• identify the elements required to establish the defence of necessity
• distinguish necessity from other defences such as consent or self-defence
• apply the principles of necessity to specific factual situations presented in multiple-choice questions.

Test Your Knowledge

Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, remember to look more closely at that area during your revision.

1. Which of the following is an essential element for the defence of necessity to succeed?
   1. The defendant acted with the claimant's implied consent.
   2. The defendant acted to protect their own property interests exclusively.
   3. The defendant reasonably believed there was an immediate and real danger.
   4. The defendant's actions were authorised by statute.
2. In which situation is the defence of necessity most likely to be successfully pleaded?
   1. A driver exceeding the speed limit slightly to arrive at a meeting on time.
   2. A person damaging a neighbour's fence to retrieve their pet cat.
   3. A firefighter breaking down a door to rescue occupants from a burning building.
   4. A company polluting a river slightly to avoid the higher cost of proper waste disposal.
3. The defence of necessity requires the defendant's actions to be:
   1. Intentional and malicious.
   2. Reasonable and proportionate to the danger faced.
   3. Agreed upon by all parties involved beforehand.
   4. The least expensive option available.

Introduction

In certain limited circumstances, a defendant whose actions would otherwise amount to negligence (or another tort) may escape liability by pleading the defence of necessity. This defence applies where the defendant deliberately commits an act, potentially causing damage, in order to prevent a greater harm from occurring. It arises from situations of imminent danger where the defendant is forced to choose between two evils. Unlike defences such as consent or contributory negligence, necessity does not depend on the claimant's conduct but rather on the urgent circumstances facing the defendant.

Key Term: Necessity A defence in tort law where the defendant argues their actions, although potentially harmful, were necessary to prevent a greater evil due to an imminent danger.

The defence is narrowly constructed by the courts to prevent its abuse as a justification for otherwise tortious conduct. Its successful application hinges on proving specific elements related to the danger faced and the reasonableness of the defendant's response.

Elements of the Defence

For the defence of necessity to succeed, the defendant must establish two primary elements on the balance of probabilities:

1. Imminent Danger: There must have been an immediate and real danger or threat requiring urgent action. The threat must be directed towards the defendant, a third party, or the defendant's or another's property.
2. Reasonable and Proportionate Response: The action taken by the defendant must have been reasonably necessary in the circumstances to avert the threatened harm, and the harm inflicted by the defendant's actions must not be disproportionate to the harm sought to be avoided.

Imminent Danger

The danger faced must be immediate and objectively real, not merely perceived or speculative. The defendant must reasonably believe that intervention is required to prevent harm.

Key Term: Imminent Danger An immediate and pressing danger that requires urgent action to prevent harm occurring.

Worked Example 1.1

A lorry driver's brakes fail while descending a steep hill towards a crowded pedestrian crossing. To avoid hitting the pedestrians, the driver swerves into an empty shop front, causing significant property damage. Can the driver rely on necessity?

Answer: Yes, likely. The driver faced an imminent danger (hitting pedestrians). Swerving into the shop, while causing damage, was arguably a reasonable and proportionate response to prevent loss of life or serious injury, which represents a much greater harm.

Reasonable and Proportionate Response

The courts assess the defendant's actions objectively: would a reasonable person in the same position have acted in the same way? The response must be necessary – meaning no reasonable alternative was available – and proportionate. Proportionality involves balancing the harm caused by the defendant's actions against the harm they were trying to prevent. Causing greater harm than the harm avoided will defeat the defence.

Exam Warning

Do not confuse necessity with self-defence. Self-defence involves repelling an unlawful attack, often from the claimant. Necessity involves reacting to an imminent danger which may not stem from the claimant's actions (e.g., reacting to a natural event or a third party's actions).

Worked Example 1.2

During a severe storm, a homeowner demolishes their neighbour's unstable garden shed, fearing it will collapse onto their own house and cause extensive damage. The neighbour sues for trespass and damage.

Answer: The homeowner might plead necessity. They faced an imminent danger (potential damage from the collapsing shed). Demolishing the shed was the action taken. The court would assess if this was reasonable and proportionate. Factors include the actual likelihood of collapse, the potential damage to the homeowner's house versus the value of the shed, and whether less destructive alternatives existed (e.g., alerting the neighbour, temporary supports). If demolishing the shed caused disproportionate harm compared to the risk averted, the defence may fail.

Scope and Limitations

The defence of necessity is tightly controlled and subject to several limitations:

• Self-Created Danger: The defence is generally unavailable if the defendant's own negligence created the emergency situation in the first place.
• Availability of Alternatives: If a reasonable, less harmful alternative course of action was available, the defence will likely fail.
• Public vs Private Necessity: Sometimes a distinction is drawn between 'public necessity' (acting to protect the public good) and 'private necessity' (acting to protect private interests). Public necessity may justify causing greater harm than private necessity. Southport Corporation v Esso Petroleum Ltd [1956] AC 218, where oil was discharged to save a ship and crew (arguably public necessity), is a key illustration, though the defence ultimately faced challenges on other grounds in that case.
• Medical Cases: Necessity can be relevant in medical emergencies where a patient cannot consent (e.g., unconscious). Treatment necessary to save life or prevent serious harm may be justified. However, this intersects with principles of capacity and best interests under the Mental Capacity Act 2005. Re A (Children) (Conjoined Twins: Surgical Separation) [2001] Fam 147 is a significant, though extreme, example involving the separation of conjoined twins where one would inevitably die.

Revision Tip

Remember that necessity is a defence of last resort. The defendant must demonstrate that they had no reasonable alternative but to act in the way they did to prevent the greater harm.

Key Point Checklist

This article has covered the following key knowledge points:

• Necessity is a defence in tort, applicable when a defendant acts to prevent greater harm due to imminent danger.
• Two core elements must be proven: imminent danger and a reasonable and proportionate response.
• The assessment of the defendant's actions is objective.
• The harm caused by the defendant must not be disproportionate to the harm avoided.
• The defence is generally unavailable if the danger was created by the defendant's own negligence.
• Necessity must be distinguished from self-defence and duress.
• Case law like Southport Corporation v Esso Petroleum and Re A (Children) illustrates its application and limitations.

Key Terms and Concepts

• Necessity
• Imminent Danger