A planning dispute in the Channel Island of Guernsey could force the Lord Chancellor, Lord Irvine, to give up his second role as a senior judge.

The move would follow a landmark hearing at the European Court of Human Rights, on whether anyone can get a fair trial before a judge who also has links to the government.

The senior judge in Guernsey also represents the island's government

The case that could change the British constitution was brought by Richard McGonnell, a Guernseyman who set up a flower growing business in the 1980s.

Times were hard and he had nowhere to live. There was a large shed on his land, used for storing and packing flowers. Mr McGonnell decided to move in.

Unfortunately, he did not have planning permission to use the shed as a home. Eventually, the Guernsey courts ordered him to turn his house back into a shed again.

Islands' own legal system

The Channel Islands are not part of the United Kingdom, they are a dependency of the Crown with their own government and their own legal system.

The decision from Strasbourg will be binding in the UK

The senior judge in Guernsey is known as the Bailiff. Presiding over the courts is certainly his main occupation. But he also presides over the island's legislature, the States of Guernsey.

And, since Guernsey does not have a Prime Minister, the Bailiff speaks for the island's government in discussions with the British government in London.

The European Convention on Human Rights says that everyone is entitled to a fair hearing by an independent and impartial tribunal. But Richard McGonnell argued that the Bailiff who heard his case was not independent of the government.

Human rights issue

That argument was supported by the European Commission of Human Rights, which filtered applications to the court until the system was changed late last year.

Lord Irvine with the wig he may have to hang up

The commission noted that when Mr McGonnell appeared before the Royal Court of Guernsey in 1995, "the principal judicial officer who sat on his case, the Bailiff, was not only a senior member of the judiciary of the island but was also a senior member of the legislature ... and, in addition, a senior member of the executive".

The commission concluded, by a majority of 25 votes to five, that it was "incompatible with the requisite appearances of independence and impartiality for a judge to have legislative and executive functions as substantial as those in the present case."

The case will be heard by the European Court of Human Rights on 28 September. The court often takes the same view of the law as the commission, so there is every chance Richard McGonnell will win.

Implications for Irvine

If that happens, the Bailiff may have too give up some of his non-judicial functions.

But success for Richard McGonnell would have implications far beyond Guernsey. The Lord Chancellor, Lord Irvine, also has a foot in more than one camp.

He is a leading member of the cabinet; he acts as speaker of the House of Lords; and he sits from time to time as the senior law lord to hear appeals from lower courts.