Should sex offenders be given lie detector tests?

There is probably no less popular group of people in this country than sex offenders. That's unsurprising, and you certainly won't find me with anything nice to say about them. They are, however, human beings and as such have a right to be treated in a fair and just way by the authorities, the same as you or I. Why? Because once you start picking and choosing who gets human rights and who doesn't, life gets very nasty. Like the old poem says, if you don't stand up when the rights of others are violated, there won't be anyone to stand up for you.

That's why I feel deeply uneasy that lie detector tests have in the first place been used on sex offenders living in the community in England and that the apparently successful pilot has been extended.

Why exactly does it scare me so much?

First of all, how do we actually know that the results are accurate? This USA Today article confirms pretty much what I feared, that the results are open to subjective interpretation. If you hooked me up to one of these machines and started asking me questions that were designed to trip me up, and I didn't trust you, you can bet your life I'd look like I was lying even if I was reading nursery rhymes. You bet I'd be feeling anxious. So, if someone "failed", would they be sent back to prison on a false premise. We should be very concerned about people's liberty being taken away unnecessarily.

Second, if we're going to rely on lie detector tests, do we then not become a bit lazier about evidence. Forgive me, but I don't have a whole load of confidence in the US judicial or penal system. This monitoring of sex offenders by polygraph is an idea that comes from there and I inherently distrust it.

Thirdly, there's the slippery slope argument. If this is such a success who next? Terror suspects? Immigrants? Schoolkids returning from a period of absence? Benefit claimants?

Fourthly, success is apparently being determined by the fact that more offenders 'fess up to doing things they shouldn't to their probation officers. Or, to be more accurate, things that they already have done.Can you see where I'm going here? The potentially dangerous moment has passed. Somebody could already have been hurt. Surely, if we want the public to be safe, we need to be thinking about better psychological support and better rehabilitation for these offenders so that the breaches of licence are less likely to happen in the first place?

What do you think about this? Does anyone have any words of reassurance for me on a civil liberties front? Frankly, I'd be surprised, but I'd be interested to hear if there are any liberal arguments in favour of such a scheme.