Mr Straw understands perfectly well that where people are protecting themselves or others from criminal attack they are already entitled to deploy "reasonable force". Granting additional licence would mean endorsing a measure of unreasonable force, a position which would be indefensible and possibly illegal. That logic underpins the existing law, and has seen off repeated attempts to change it. The first impulse for an overhaul came from William Hague's Conservatives after the farmer Tony Martin was jailed for fatally shooting a teenager who had broken into his house. The real outrage arose because of the mandatory life term Mr Martin initially received. A rational response would have been to do away with inflexible minimum sentences. Instead the reasonableness test became the controversial issue. Later, in the wake of renewed Tory pressure, Tony Blair conceded a review which concluded in 2005 that the current law was sound. Pressed yesterday on what had changed since then, Mr Straw was left floundering.
Reassuringly, the justice secretary was clear that it must remain illegal for the likes of Tony Martin to kill intruders. He also accepted that citizens who have deployed reasonable force very rarely end up in court, and that when they do, they mostly secure fair verdicts. He accepted, too, that the current law works "better than most people think". So why, exactly, did Mr Straw decide to reopen this dormant but explosive issue? His only answer was that it was unfortunate when citizens who had acted appropriately were put under police investigation. And so it is. But without an investigation it is hard to see how it could be established that the behaviour was, in fact, appropriate.
The more plausible aim of yesterday's move was to unsettle the opposition. Traditional Tories feeling exasperated with their leader could become even more so when campaigns that their party used to lead are instead being launched by the government. One former colleague memorably admired the "guile and low cunning" of Mr Straw, which was again in evidence yesterday. But as the Police Federation rightly argued, such politicking risks inflaming expectations that cannot be met and undermining confidence in the law.