Must MPs always vote before we go to war?

Jesse Norman was permitted three minutes for his speech to the Commons in last Friday’s debate. But the contribution from the Conservative MP for Hereford & South Herefordshire was one of the more important backbench interventions — and no less important for being wide of the debate’s focus.
The House was being invited to support British intervention against the Islamic State. Mr Norman’s speech was about whether the invitation was even appropriate. As he put it, ‘A convention has started to develop that, except in an emergency, major foreign policy interventions must be pre-approved by a vote in Parliament.’ The MP thought this unwise.

I disagree. Or half-disagree. But ­Norman’s case was powerful, and I shall give you the gist. He is all in favour of debates, questions or statements on military action; he thinks them vital; but he objects to the emerging rule that ‘a prior authorising vote’ should be required. ‘The plain fact is,’ he said, that in matters like this, ‘members of the House are inevitably far less well informed than ministers who follow and reflect on the issues every day. We do not have the same access to officials and advisers; we are not privy to diplomatic traffic or secret intelligence; and we are not briefed by, and may not demand briefings from, our armed forces. As a large corporate body, we lack the capacity to react quickly and without warning to fast-­changing events. The result is delay and a loss of agility and surprise, which ill serves our forces in the field.’
Norman’s second argument was that a Commons authorisation, once made, ‘binds members in their own minds, rather than allowing them the opportunity to assess each government decision on its own merits… Ministers can always take final refuge in saying, “Well, you authorised it.”’
I must dismiss that second argument out of hand.