Leading article: Now BP has made its ritual sacrifice, we must regain a sense of proportion

The term kangaroo court is not, as might be supposed, Australian.

It is American and it dates from the California Gold Rush, when miners established places of rough justice to deal with claim jumpers. Seeing the chief executive of BP, Tony Hayward, in front of a US Congressional committee this week, it could be concluded that America has lost none of its appetite for emotive summary justice.

It was an unedifying performance all round. The politicians were distinguished more by a barrage of outraged statements and claims, rather than probing or insightful questioning. The protesters allowed in with their anti-BP banners, along with the tar-daubed heckler, only added to an impression of more heat than light. But then Mr Hayward did not make life easy for himself.

True, he had to suffer more than an hour's lambasting in silence before he was allowed to speak. But when he did, he contrived, no doubt at the insistence of BP's lawyers, to say very little. According to one count, he replied "I don't know" more than 65 times. In one sense all this is understandable. This is the worst environmental accident the US has ever suffered; 11 people died and the livelihoods of tens of thousands have been compromised.

Set against that, BP – despite some cack-handed statements by its bosses – has mobilised thousands of conservationists and has already paid compensation to 18,000 people. It has identified seven key areas in need of investigation, begun that process and vowed that action will be taken against anyone found guilty of putting costs ahead of safety. And this week it has agreed a $20bn fund with President Obama to cover the cost of clean-up and compensation; $20bn is serious money, even to a giant oil firm.

But more will be achieved with a spirit of co-operation than with the kind of confrontation seen this week, which had about it the high hysteria of the lynch mob. Most disturbing was the politicians' insistence on calling BP, which changed its name 12 years ago, by its old title, British Petroleum. There is a facile nationalist populism about that. There is a lie at its heart, too, for BP has more American shareholders than British. But there is a grave danger in such obscurantism. It will benefit neither side of the Atlantic if a company like BP, in which all our pensions have shareholdings, is pushed into crisis because of the posturing and pandering of a group of US politicians who, significantly, are facing re-election in November.

To date, the British Government has walked a nicely judged line. The Energy Secretary, Chris Huhne, has made clear its sympathy for the US administration's determination to make BP pay in full for the massive oil spill. But the Prime Minister has also privately told Mr Obama that it is in no one's interests to push BP to the wall. The danger is that the deal the US President has forced from the company could prove open-ended, with claims for lost trade from every small business in Louisiana. Washington and London should both understand that, now the ritual sacrifices have been made to the gods of politics, a sense of proportion must be maintained for as long as it takes to work through the consequences of this disaster.