Leading article: When will political life return to normality?

In the aftermath of a terrorist attack, a symbolic unity across the political spectrum is understandable and, on one level, wholly desirable. Political leaders have a duty to unite in sending out clear messages of condemnation. But beyond these broad affirmations, consensus becomes a tame substitute for rigorous debate and scrutiny. There is a stifling assumption that to break the unity would be conceding ground to the terrorists.

The opposite is the case. Terrorists win some kind of victory when elected politicians feel unable to express doubts about what the Government is doing. Before the attacks, many Conservatives, Liberal Democrats and indeed some Labour MPs had deep concerns about the proposed anti-terrorist legislation. Although the attacks confirm bleakly that London, and possibly other parts of Britain, face a terrible threat, they should not in themselves suddenly silence all debate. Presumably the opponents of the proposed laws formed their opinions aware that an attack was possible or indeed probable. In the autumn, the Government proposes to outlaw indirect incitement to terrorism, acts preparatory to terrorist attacks and training for terrorism. The first two of these are not easy to define, and could lead to heightened tensions in local communities.

When does a sermon move from irresponsible propaganda to incitement to terrorism? How do you prove "preparatory" acts? The difficult questions are not an automatic reason for opposing attempts to legislate. But these are questionable measures, and in a febrile situation political leaders have a duty to scrutinise with even greater care than normal. As we have seen all too often, legislation made in haste is rarely good legislation.

Inevitably, a crisis of such complexity will throw up many other contentious issues. A brief survey of radio phone-ins, letters pages and newspaper columns suggests that opinions on the new "shoot-to-kill" policy range widely. But political leaders and most MPs are not inclined to ask many questions. They should do so. A change of policing strategy in which one innocent person has already been killed is a legitimate topic for debate.

Similarly, the bombs in London should not silence questions about Britain's role in the war against Iraq. Politicians who dare to raise Iraq are not seeking to justify terrorism, as Mr Blair implied at his press conference yesterday. Has the war fuelled terrorism, as the intelligence warned that it would? How long should British troops remain in Iraq? A handful of more courageous politicians have raised these questions since 7 July, including Charles Kennedy and Robin Cook, but mostly Iraq has become a political taboo.

Acts of terrorism deserve sweeping condemnation across the political spectrum. But they also raise complex questions in a democracy facing an unprecedented threat from suicidal attackers raised within its borders yet seemingly inspired by global events. There must be strict limits to the new consensus; our politicians have a duty to lead the public debate.