That is the law in Britain, a regulatory tribunal declared this week. The tribunal ruled that Deloitte L.L.P. had failed in its professional responsibilities in its work for MG Rover, the failed automaker, and for the “Phoenix Four,” four businessmen who took over the automaker in 2000 and ran it into the ground, taking out millions of pounds for themselves in highly dubious transactions before the company failed.

The tribunal issued a “severe reprimand” to Deloitte and levied a fine of £14 million ($22 million) against the accounting firm, a record in Britain. It fined Maghsoud Einollahi, a retired Deloitte partner, £250,000 and barred him from the profession for three years.

“They placed their own interests ahead of that of the public and compromised their own objectivity,” said the tribunal, convened by the Financial Reporting Council. “This was a flagrant disregard of the professional standards expected and required.”

Deloitte was the auditor for MG Rover, but the audits have not been challenged. Instead, it was the corporate finance work, run by Mr. Einollahi, that drew the condemnation.

The ethics rules of the Institute of Chartered Accountants in England and Wales — a group that all accountants and accounting firms must belong to — require accountants to consider the “public interest.” This ruling appears to be the first that makes clear just how far that can go.

“It has been put to us that in corporate finance work and tax work the only duty that a member owes is to his client, provided that he acts with integrity, and that the public interest is not a matter that needs to concern him,” the tribunal wrote. “We do not accept this.”

British auditing firms have gained some success in competing with investment banks in providing advice on mergers and corporate restructurings and have been able to charge high fees that are contingent on success of a transaction. The ruling did not say such fees were barred, but it did say that accounting firms must carefully guard against conflicts of interest.

It conceded that the requirement to take the public interest into account could make it harder for accountants to win such business, but said that did not matter. “It is this duty to consider the public interest that provides comfort to the client that matters are being dealt with properly and with integrity.”

Deloitte argued that the public interest was not involved because MG Rover was a private company. The board rejected that, noting that Deloitte itself bragged about its role in preserving jobs when the Phoenix group took over MG Rover from BMW, the German carmaker, and that Mr. Einollahi cited the public interest in preserving jobs when he wrote to British tax authorities seeking favorable tax rulings.

In 2000, BMW concluded that it had made a mistake in acquiring MG Rover and set out to find a buyer. After one deal fell through, it settled on a company called Phoenix Venture Holdings, which bought the company for £10.

Even that nominal price drastically overstated what was paid. BMW chipped in what was called a dowry — a £427 million interest-free loan for up to 49 years.

That loan became the source of some of the money the businessmen took out of MG Rover before it failed in 2005. Rather than have the loan go to the car company, the Phoenix Four directed it to their parent company, which then lent the money to the car company, charging interest. They then distributed the “profits” that they realized from the interest to themselves.

Another strange deal involved the men’s being owed £10 million by the company even though they had invested only £60,000 each.

They wanted the figure to be £75 million, but that arrangement could not be completed. According to a later government report on the fiasco, Peter Beale, one of the Phoenix Four, blamed Sue Lewis, a partner in Eversheds, a prominent law firm that was advising the company, for keeping them from realizing the full amount.

Ms. Lewis testified that Mr. Beale had told her “it wasn’t her position to be raising questions about the directors’ remuneration and that she had done it on a number of occasions in a way that he had thought was inappropriate.”

The law firm, Mr. Beale said, was not “anybody’s moral guardians.”

Floyd Norris comments on finance and the economy at nytimes.com/economix.com