Self-defence is crucial not only for safeguarding the security officer but also for protecting, customers, and members of the public who may be in harm’s way. To address this need, UK law permits the use of ‘reasonable force’ when an individual or those nearby are under threat. However, the legal definition of reasonable force can be vague and is often open to interpretation, which can create uncertainty.
This article aims to clarify what constitutes ‘reasonable force’ and ‘excessive force,’ as well as to explain the principles of self-defense and when the use of force is appropriate.
What Is ‘Reasonable Force’?
‘Reasonable force’ refers to the level of force necessary to defend yourself, others, or your property from unlawful aggression or harm. The key to reasonable force is proportionality—it must match the level of threat you are facing at that moment. If the force used exceeds what is necessary, it could be deemed ‘excessive force,’ which is not legally permissible.
UK law intentionally avoids providing a rigid definition of reasonable force because every situation is unique. For instance, if someone encounters an armed intruder in their home, it might be considered reasonable to use a weapon for self-defence. In contrast, using a weapon against an unarmed, albeit aggressive, person could be judged as excessive.
While the concept of reasonable force is designed to be flexible, it is ultimately subject to interpretation by what is deemed reasonable by the average person, which can lead to confusion.
When Is Reasonable Force Permissible?
Reasonable force is generally acceptable in two main scenarios:
In the heat of the moment: During or immediately before a violent incident when a threat is perceived to be imminent.
To prevent escape: When a perpetrator is attempting to flee the scene of a crime and needs to be restrained.
In legal contexts, citing the use of reasonable force can be a strong defence in criminal trials or civil suits alleging excessive force. This defence is often supported by evidence such as CCTV or body camera footage. However, it is crucial to demonstrate that the force used was truly reasonable and within legal bounds, as this must be established beyond any reasonable doubt.
Remember, the force you apply must always be proportional to the threat you believe you are facing at the time. The law supports your right to defend yourself and others, but it also holds you accountable for ensuring that your actions are justified and appropriate given the circumstances.
Understanding ‘Reasonable Force’?
In situations where force is used, the key to remaining within the boundaries of lawful conduct is whether the amount of force was proportionate to the threat faced at the time. If an individual can demonstrate that their response was equal to the level of threat, they are unlikely to have breached the law.
Everyone in the UK has the right to defend themselves from harm and to protect others. Acting in self-defence, including tackling and restraining someone engaged in criminal activity, is generally permissible. The concept of reasonable force is dynamic and typically escalates in line with the severity of the threat.
The law also acknowledges the impact of the ‘fight or flight’ response—also known as hyperarousal or acute stress response—during high-stress situations. Section 76(7) of the Criminal Justice and Immigration Act 2008 states:
“A person acting for a legitimate purpose may not be able to weigh to a nicety the exact measure of any necessary action; and (b) …evidence of a person’s having done what the person honestly and instinctively thought was necessary for a legitimate purpose constitutes strong evidence that only reasonable action was taken.”
This means that in the heat of the moment, lapses in judgment are natural and expected. A person might overestimate the level of threat they face, and the law recognises that such actions may still be deemed reasonable or as self-defence.
However, once a threat has been neutralised, continuing to use force is not considered reasonable. For example, if an attacker has stopped fighting or is no longer a threat, any further assault would be unlawful. Similarly, it is illegal to set a premeditated trap for someone, such as inviting a person over with the intention of attacking them.
When cases of alleged assault, battery, or excessive force are brought to court, two key questions are considered:
- Did the person using force genuinely believe it was necessary?
- Was the force used proportionate to the threat faced at the time?
If the answer to both questions is ‘yes,’ then the force is likely to be deemed reasonable under the law. Therefore, if you find yourself in a situation where force might be necessary, it is crucial to mentally ask yourself these questions before taking action.
Legal force may be used to protect oneself or others from imminent danger, to prevent crime or assault, to search someone, to defend property, or when assisting in the lawful arrest of a criminal.
For security guards, limited force may be employed to escort uncooperative trespassers from the premises they are guarding. However, any use of force must be strictly in self-defence or the defence of others; excessive force or harm is not permitted.
When Can Reasonable Force Be Used?
Reasonable force can be applied in situations involving violence or crime, particularly when it is necessary to protect oneself or others who may be at risk of harm. This includes not only defending against an ongoing attack but also acting preemptively to prevent an imminent assault.
For instance, if someone raises their fists in a threatening manner, you do not need to wait for the blow to land before taking action. In such a scenario, restraining the potential attacker to prevent the assault is considered reasonable force. However, factors such as the size, weight, and physical condition of both parties will be taken into account. For example, a large, strong individual claiming self-defence against a frail, elderly person may be scrutinised and possibly deemed excessive.
Other key considerations include whether the use of force was necessary at all, when the force was stopped, and whether there was any malicious intent involved. These factors help distinguish reasonable force from excessive force.
When Does Reasonable Force Become Excessive Force?
Once a person is no longer under threat, any further use of force may be considered excessive. If someone transitions from defending themselves to actively attacking when the threat has diminished or ceased, they are likely engaging in excessive force, which is a criminal act under UK law.
Reasonable force is proportional and generally permissible, whereas excessive force is disproportionate and never acceptable. Examples of excessive force include continuing to beat someone who is already incapacitated or unconscious, or chasing down and assaulting a fleeing person instead of simply restraining them.
Even in less extreme cases, excessive force might involve physically restraining someone who is not complying with verbal commands or making verbal threats against someone who is being aggressive. Essentially, any use of violence outside the context of self-defense, or any force that is grossly disproportionate to the threat at hand, is considered excessive force. This includes any actions driven by malice or revenge.
As previously discussed, the legal definition of reasonable force is intentionally broad, recognising that people may react irrationally in high-stress situations. Consequently, there is some flexibility in the interpretation of these actions. If force slightly exceeds what is necessary in self-defense, it is unlikely to result in prosecution.
In extreme cases, reasonable force may even extend to causing the death of an assailant, provided the assailant posed an equivalent level of threat, and the measures used were both the only option available and a last resort. Such instances are typically ruled as self-defense rather than manslaughter or murder.
The definition of reasonable force is deliberately vague, which means that while the definition of excessive force is more concrete, it still relies on the interpretation of what is considered reasonable.
We hope this guide has helped clarify these concepts and made them easier to understand. The SIF will always support it’s members when reasonable force is used providing it is necessary and proportionate.
