Law lords said the London Borough of Haringey’s 2012 exercise on its proposal to deal with a funding shortfall caused by Council Tax Benefit reforms was unfair because it had failed to set out alternatives to its choice, hindering residents’ ability to offer their own views.
While the decision itself is unrelated to planning issues, commentators said Moseley v Haringey sets expectations about proposers’ preferred options and the reasons for them. It also entails that rejected options should be presented as part of consultations, they added.
The judgement also gives what is seen as the first Supreme Court endorsement of previous case law on what constitutes a "fair" consultation conducted to inform proposals.
Tom Henderson, legal director for government and infrastructure at law firm Bircham Dyson Bell, said the case would be likely to be relevant to a range of statutory and voluntary planning-related consultations.
"Because of the length of time it takes to consult, promoters are often keen to narrow down what they want to consult on," he said.
"This case suggests that while you can have a preferred option, you need to make sure you show your working," he added.
"Those undertaking consultations ought to be providing details of options that they are not proposing to take forward, if only to set out what the context is and allow people to express their opinions on that."
Robbie Owen, head of infrastructure, planning and government affairs at law firm Pinsent Masons, suggested that the judgement would be likely to "strengthen the focus" of promoters and it could also guide expectations at the Planning Inspectorate.
"If there’s an obligation to consult and people think that it’s done badly, then you have to go back and do it again. This raises the bar on what ‘you must consult’ means," he said.
"In reality this will just help to illustrate what consultation might require in cases where there are a range of options," he added.
James Anderson, head of engagement at consultancy Turley, said: "Major infrastructure schemes that evolve over a long period of time tend to have very detailed, complicated consultation questions.
"One of the consequences of this judgement will probably be a drive to make consultations on complicated Nationally Significant Infrastructure Projects clearer for people who are not experts."