The House of Lords' ratification last week of environment secretary John Prescott's power to intervene in development issues has derailed planning reform in the UK, according to Town and Country Planning Association director Gideon Amos.
Amos said the Lords' decision could mean that the planning system was incorrectly seen as trouble-free.
'It is misleading, because people might well infer that there are no problems in planning - and this is not the case, ' Amos said.
'There are cases in which a minority of people still suffer a degree of injustice at the hands of the planning system and this decision will bring no comfort to them, ' he added.
'What we need to do is to work across the sectors to see if there is a way in which sensible reforms can be brought about and to address problems without causing delay to the planning process.'
A High Court ruling that Prescott could not intervene in large or controversial planning decisions, or play a part in planning appeals, was overturned by the House of Lords in favour of an appeal by the environment secretary.
The ruling confirmed the government's ability to intervene in large decisions without having to defer to an independent planning tribunal.
The High Court decided that the planning system was incompatible with the Human Rights Act and that Prescott could not make both policy and independent decisions.
But the House of Lords disagreed. It ruled: 'In the democratic system of government in England, a minister could properly perform both functions because he was answerable to Parliament as regards the policy aspects of his decision and answerable to the High Court as regards the lawfulness and fairness of his decision-making process'.
Royal Town Planning Institute spokesman David Rose said the government was now free to look at the planning system in its entirety.
'The basic integrity of the system has survived, ' he said. 'We think the way is clear to press on with the review of the planning inspectorate and the way in which big enquiries are dealt with.'
But Rose said the ruling opened the way for further legal challenges based on the Human Rights Act - for example, whether there would be a right of appeal in the listing of historic buildings or sights of scientific interest.
However, David Brock, planning partner at Cambridge law firm Mills & Reeve, said he remained convinced that Prescott's powers of intervention are at odds with the Human Rights Convention, which states that everyone is entitled to a fair and public hearing within a reasonable time by an independent and impartial tribunal established by law.
'The minister is not independent or impartial.
The minister, who makes the national policy on planning, has a point of view, ' Brock said.