Following a planning inspector's public examination of the plan, it was formally adopted by the council in April this year.
But local campaigner, Julian Cranwell, joined Compton and Ockham Parish Councils in mounting a judicial review challenge to the plan.
In his recommendations to the council, the examining inspector calculated that 562 homes need to be built in the Guildford area every year until 2034.
That meant a total of 10,678 new homes over the plan period, which he said could only be achieved by re-drawing green belt boundaries.
If all the proposed development sites detailed in the plan were built on, 14,602 new homes would potentially be delivered over the plan period.
But the inspector said that "headroom" was needed to take account of unexpected contingencies, including slippage or non-delivery of development projects.
The inspector also said the "very high level of need" for more affordable homes in the area justified setting housing targets well above historic rates.
Alterations to the green belt boundary, he added, would not cause severe or widespread harm to the openness of the area.
Cranwell, a member of the Guildford Green Belt Group, which is represented on Guildford Council, and the parish councils mounted a wide-ranging attack on the inspector's conclusions.
His assessment of the area's housing need was excessive, they argued, and there were no exceptional circumstances to justify the loss of so much green belt land.
The headroom the inspector allowed would mean almost 4,000 more homes being built over the plan period than the council objectively needed, they argued.
Also under challenge in court were specific development proposals at Blackwell Farm, to the west of Guildford, and at Wisley Airfield.
Development of Blackwell Farm for 1,800 homes and a research park use is being promoted by the University of Surrey.
The local plan allocates 2,000 homes on 96 hectares at the former Wisley airfield.
Plans for the residential development of sites to the north of Horsley railway station and at Gosden Hill Farm also hinged on the outcome of the case.
Dismissing the challenge to the local plan, the judge, Sir Duncan Ouseley, said it needed to be "robust" enough to meet the area's housing needs for years to come.
He emphasised the consequences that would arise if none of the sites in issue were released from the green belt and allocated for housing.
That would, over the plan period, produce a shortfall of 6,295 homes when measured against the inspector's target figure of 14,602.
The inspector had said a headroom figure of almost 4,000 homes was needed, over and above the area's assessed housing need.
And the judge said he had given "clear and adequate reasons" for that conclusion.
"I see nothing illogical in the inspector's thought process, requiring a buffer of some significance," he told the court.
The inspector was entitled to find "exceptional circumstances, strategic and local" justifying the release of green belt sites, said the judge.
Given that 89 per cent of the council's area is covered by green belt policy, the inspector had justifiably concluded there was no prospect of employment, business and housing needs being met over the plan period without releasing parts of it for development.
The judge said he was also entitled to take into account that the release of more housing land from the green belt would help tackle "pressing housing problems" in the Guilford area, particularly the scarcity of affordable homes.
Compton Parish Council & Ors v Guildford Borough Council & Ors. Case Number: CO/2173/2019