David Turpin and his wife were involved in a legal battle with the local government ombudsman over a property dispute.
In a rare move, the High Court in London has ordered the ombudsman to carry out a proper investigation into the couple's case.
The judge also ruled that confidential reports and interviews should not be kept from complainants unless there were very good reasons for doing so.
Solicitor Richard Buxton agreed to represent the Turpins, from Cambridge, after hearing of their dispute during a call-out.
After the hearing Mr Buxton said: "This is quite a blow for the conduct of local government administration.
"It basically means the ombudsman will have to pull his socks up and there will be much better scrutiny of his procedures.
"The ombudsman will no longer be able to hide behind confidential investigations which he does not then disclose to those making complaints."
Houses built
The couple's dispute centred around a detached house in Cambridge they had built for their retirement in 1991.
They protested to Cambridge City Council after a block of six houses, which had been erected on adjoining plots, were built too close to their home and threatened to reduce its value.
When they had no success with the council, they contacted the local government ombudsman.
But the ombudsman refused to investigate their complaint of maladministration.
Mr Buxton said: "It is very, very rare to bring a successful challenge against the ombudsman.
"This has been a battle that has been going on for a very long time, but my clients are now vindicated."