Use of Force – Decision Making

I recently read the excellent blog by Sir Robert Peel on Police Use of Taser which considers decision making and conflict management through the National Decision Making Model (NDM). This links nicely to my own recent blog Use of Force, which examined the Force Continuum. In this blog, I will try and draw together the force continuum and NDM, examining how they compliment each other and assist in decision making in circumstances where force may be used.

The National Decision Making Model

This model has been introduced recently to replace the conflict management model (CMM), although there is not much difference between them. ACPO felt that the CMM was an excellent decision making model, but that the name discouraged it use for wider decision making. An ACPO guidance paper explaining the model is available on their website.

The NDM has five stages each of which is a step in the decision making process, it is cyclic allowing decisions to be reassessed and debriefed in light of new information. The only major differences between the NDM and the CMM are that the NDM has a pentagon in the centre that links to each step and the direction of the cycle was changed, the CMM cycled anti-clockwise while the NDM is clockwise.

Step 1 – Information/Intelligence

In this stage, the officer will identify what they know and how they know it. I think of this as assessing

1. Known knowns – information and intelligence that is known (intelligence is information that has been assessed and given a rating based on how it is known and the source.)
2. Known unknowns – information that the officers doesn’t know, but which they know they don’t know. The officer then needs to assess whether they can find the information and whether they need to act before they can obtain the information.
3. Unknown unknowns – the low bowlers that catch people out, it’s easy to say there shouldn’t be any, but it is worth being prepared for the unexpected.

Step 2 – Threat and Risk

The officer then assess the threat and risk to the victim, to the subject, to police officers and to the wider community; this threat is then assigned a probability (risk) either low, medium, high or unknown. Any unknown risk should be treated as high. The officer should also consider whether immediate action is required to mitigate the risks.

During this step, the officer considers the known unknowns because these can impact upon the risk assessment and judges whether these gaps can be filled.

Following these assessments a working strategy will be developed, basically stating what is to be achieved; this would normally be along the lines of maximising safety of officers, reducing risk to victim and public and apprehending the offender.

Step 3 – Powers and Policy

Now the officer considers what police powers are needed, what his duty as a police officer requires (e.g. s17(1)(a) Police (Scotland) Act 1967), what legal powers will be needed or may be used (for instance power of arrest, power of entry) and what local or national guidance is available.

Step 4 – Tactical Options

This is where the force continuum comes into play,


The officer identifies tactical options from the continuum, remembering to account for the special factors that can impact upon the desired tactic. It must be remembered that the option to disengage and tactically withdraw is important, many officers find this a difficult step to take; however, it is not retreating, but removing yourself from danger and maintaining vigilance until appropriate resources can attend.

The options should be assessed in terms of the Human Rights of the victim, the subject, the police officer and the wider community and finally tested against the question, is this option reasonable considering all the circumstances?

It is also important to consider contingencies for when the unknown unknowns rear their head.

Step 5 – Action

It is now the time to take the action; put the decision into practice.

Since the model is cyclic, it doesn’t stop at Step 5, but returns to Step 1, either to identify further options in light of a changed situation or to debrief the action and identify future learning opportunities. This is known in policing as ‘spinning the model.’


Mission and values are not a step in the wheel, but rather the axle on which it spins


Many officers find this confusing but, put simply, when using the NDM every step in the process should be assessed against the very simple questions

1. Is what I am doing consistent with my duty as a police officer to act with integrity, be willing to take risks and protect the human rights of all?
2. What would the police expect of me in this situation?
3. What would the victim, the affected community and the wider public expect of me in this situation?


The NDM appears complicated when explained in a step by step way like this, however that is a result of mapping processes. Think about the steps involved in brewing coffee, there are about 10 steps and it would take a lengthy blog to detail them, however, I can make a cup of coffee very quickly despite the lengthy process; it is the same with the NDM, police officers trained to use it make almost instant decisions following its principles and it provides the ability to rationalise decisions.

The following example will hopefully illustrate this.

A police officer gets called to a report of shouting from an address. Whilst attending they spin the model, they have no real information or intelligence, they cannot make an accurate assessment of the threat and risk so the working strategy is to get more information, the officer has a duty to prevent disorder and keep the peace, but cannot make a full assessment of powers required until more information is available, the options are to get more information by tasking the control room to develop this and by making their way to the address to assess and gather information. This is reasonable and human rights compliant, so the officer undertakes these actions. This process takes about 100 words to explain, but an officer would make this assessment in the blink of an eye.

On attending at the address, they see a man in the street with his shirt off swinging a large block of wood, while on route to the address, research has revealed that the subject is known to police for violence and alcohol abuse. The model is spun again with this new information, the threat/risk to the subject, police and wider public is assessed as high. There is unknown factors (is there anyone in the house?) The working strategy is now based around maximising the safety of the community, minimising the risk to police, identifying potential victims and apprehending the subject. The subject has committed a crime and can be arrested, the assessment of options, looking at the force continuum includes use of incapacitant spray or taser, particularly given the special circumstances of the subject (known to abuse alcohol and be violent) however, if there is no immediate danger, then speaking to the subject would be considered along with tactical withdrawal. The officer would then act according to the options considered.

The model would be spun numerous times during a situation like this every time a new piece of information or intelligence became available until the situation was resolved and debriefed. As a supervisor attending an incident like this, I would expect to be briefed by the attending officers using this model.


About PoliceGeek

I am a police sergeant with a strong interest in policing public order, both professionally and academically. I love ultra running and seeking new challenges
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9 Responses to Use of Force – Decision Making

  1. daveincanada says:

    Makes me glad I don’t work in the UK any more: an over-complicated set of theories and procedures aimed at covering the backsides of those at the top rather than helping the people at the bottom. Im not blaming the author here, just the mess he has to work with.

    The major flaw I can see with the model is that in encourages constant (re)analysis rather than action. In your scenario the only relevant bit is that you’re faced with a drunken man armed with a lump of wood, the fact that you don’t have his date of birth, his home address or his missing medication is irrelevant, if the wood in question is baseball-bat sized, you’re going to have to shoot him, and if running away from that (sorry ‘tactical withdrawl’) is a serious ‘tactical option’ the people in charge need to have a serious word with themselves.

    One more thing: if you need to have in mind all these factors before making a decision, how come people in the control room, miles from the incident get to decide on whether or not lethal force is approved for use? I approve my own lethal force by reaching down and getting my gun out.

    • PoliceGeek says:

      And that is what is wrong with policing in the US and Canada, you have obviously entirely missed the point of my post

    • James Page says:

      navel gaze a little and while your there contemplate what public value really looks like as your suppose to be delivering it.!.The NDM ensures that discretion can be employed with public value at the heart of everything you do, and someone approving their own ‘lethal force’ doesn’t provoke potentially disastrous consequences for the tax payer and the public sector organisation.!.’Rodney King’ case in point !!!

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  6. Allan Jones says:

    Here’s the thing, what happens when you have NO time to consider the options what do you do then? The ACPO document on NDM does not allow for the spontaneous incident but fortunately here in Scotland we are taking intuitive decision making into consideration. Pre-planning for events can allow for the use of the NDM in decision making but for the frontline officer or where the unexpected happens then we need to be able to stabilise the situation before we start into slowtime decision making. To be fair to Dave he is right. The decision making model lacks one important point, identify the problem first!

  7. Graeme K says:

    As an operationally Police Inspector with over 22 years service in the UK I have applied & used the NDM countless times both slow & quick time dependant upon the situation. It works.
    Many of us with rational thought apply a decision making progress all the time with little thought about what they have done. Some people just don’t get it. Whilst shooting someone is a tactical option it is way up there for the use of force. Try being situationally aware of your environment, generate space, communicate, issue commands, use a less than least than leathal option.
    Reassess the information. By doing so you save a life & that could be you one day with a lump of wood.

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