Thank you for your query on weight of neighbourhood plans.
Regarding your question on how much weight should be given to an emerging neighbourhood plan, it is not possible to prescribe a general specific amount of weight for all emerging neighbourhood plans. The amount of weight an emerging neighbourhood plan has varies on a case by case basis and therefore when considering the weight to be given to an emerging neighbourhood plan when assessing a planning application, it is not a matter of law to determine weight, but rather planning judgement.
In the case of an emerging neighbourhood plan, in an area where there is an emerging local plan also, the decision maker when attempting to determine any weight would likely look at whether the emerging neighbourhood plan policies seem to reflect the evidence gathered for the emerging local plan. Where there is a conflict between the emerging local plan and emerging neighbourhood plan, this would likely be investigated further.
It is true that where a neighbourhood plan has been made for an area with an out of date 5 year housing supply, or where there is uncertainty around the figure, the relevant policies in the neighbourhood plan may carry less weight than for neighbourhood plans in areas where there is an up to date 5 year housing supply. However, this does not mean that these policies carry no weight at all and it very much depends on a case by case basis. For example, Mr Justice Lindblom in Crane v SSCLG  EWHC 425 was presented with a challenge to a decision made by the Secretary of State for a proposal for 111 residential dwellings in Broughton Astley in Leicestershire in an area which was not allocated for housing in the neighbourhood plan. The Secretary of State had refused planning permission on the basis that the development was in conflict with the neighbourhood plan, even though the local authority did not have a 5 year land supply and both the local plan and neighbourhood plan were out of date under the NPPF. In this case Mr Justice upheld the decision of the Secretary of State to refuse the planning permission.
Mr Justice Lindblom noted that in relation to the NPPF paragraph 14 and weighting, it is not a matter of law but of planning judgment. Mr Justice also noted that neither paragraph 49 nor paragraph 14 of the NPPF advises that policies for the supply of housing should be given no weight or minimal weight or any specific amount of weight. Instead the critical consideration for him in this case was whether the harm associated with the proposed development “significantly and demonstrably” outweighed any benefit, or that there are specific policies in the NPPF which indicate that development should be restricted. Mr Justice stated that the Secretary of State had not made a mistake in determining that the proposed development was in conflict with the neighbourhood plan even though the core strategy’s policies were out-of-date.
This example illustrates that neighbourhood plans can still have teeth and are not meaningless, even if there is no up to date 5 year supply of deliverable housing sites, as how much weight should be given to a plan with housing policies that are out of date is a matter of planning judgement.
Through our extensive work with neighbourhood planning groups, this is our understanding of the situation, however it is not formal advice/guidance; and is not a substitute for your own professional/legal advice.