Skeptics should spend more time talking about crime policy. Credulous folks on both the left and the right have dominated the discussion in a way that's detrimental. There should also be more philosophically-informed skeptics leaping into these discussions. Science is great, don't get me wrong; but it's limited to what can be measured. Not all debates, crime being one in particular, are reducible to something that can be measured.
So, you can't succeed in getting your favoured crime policy passed if you just hammer the opposition with data -- unless the dispute is actually just about data. Data don't have any bite without a set of principles that they can fit within. This is a mistake of the modern left, as well as the moderate right (classical liberals or conservatives). You can always dismiss numbers as irrelevant, and do so legitimately, if the principles underlying the dismissal really do make the numbers irrelevant.
Now, people who think about criminal justice philosophically -- so, about principles -- like to draw distinctions between different bases that might motivate criminal justice policy. Retribution is one, the idea that people who have committed crimes deserve to be punished, to suffer in some way. Rehabilitation is another, the claim that people who have committed crimes should be treated in such a way as to reduce or eliminate the possibility of future crimes. Prevention is another, the claim that people should be discouraged from committing crimes in the first place.
In isolation, these are not useful. On the one hand, yes, it's always good to have a way to think about these issues that doesn't prejudge the point of crime policy. There's lots and lots of talk about crime, as well as lots of data; without a way to sift through it all, we're basically guessing.
On the other hand, most people's thinking about crime includes some combination of a number of principles -- retributive, rehabilitative, even symbolic. Drawing distinctions can create a temptation to reduce, to look at just one dimension or feature and say that should be the point of crime policy.
So, data on its own is unpersuasive; but principles on their own lead to myopia.
The Conservative government, as is often the case with the rising (radical) right-wing these days, is clearly in retributive and symbolic mode. Rehabilitation is just not on their agenda, nor is prevention. Building more prisons and increasing sentences for minor marijuana possession are just the most obvious examples -- the idea is to punish and punish and punish, as well as to be seen to be strong and tough against criminals.
The move to revise copyright law has a similar orientation, however. The idea is to punish violations of copyright, rather than examine whether copyright makes any sense. There's also a symbolic aspect, although with a cynical guise, in that there's no possibility of the proposed copyright changes actually stopping piracy. (I suppose I could make the same point about the other two changes; I'm not sure that building more prisons is cynical, though, as something -- the actual buildings -- will come into existence.)
If you want to criticize these, then, and have those criticisms stick, it does no good to point out -- correctly -- that building more prisons or having harsher sentences doesn't reduce crime. That's not the point of the policy. The point of the policy is to make criminals pay (retribution) and to appear strong (symbolic).
Now, the left tends to be more rehabilitative than retributive. This could almost be definitional: if you favour a (relatively) retributive approach to crime, you're on the right; if you favour a (relatively) rehabilitative approach to crime, you're on the left. The left also tends to work a little more on the prevention aspect than the right.
What's interesting to me is the fact that there's a symbolic aspect to left-wing thinking about crime, too. The long-gun registry is the most obvious recent Canadian example. It was initially funny -- then progressively more disturbing -- to see folks who consider themselves on the left brow-beating others for taking a different position on the issue. If you opposed the long-gun registry from the left, you were anti-women, anti-police, pro-gun (etc, etc), and all this for agreeing with the Conservatives that the registry was a pointless waste of money.
What mattered in that case was what point the registry was supposed to serve. The Conservatives clearly saw it as representing a disdain for gun-owners. The critics from the left, including myself, saw it as an empty symbol, thus completely pointless. The supporters from the left seemed to see it as a powerful symbol. (I'm simplifying a lot, obviously.)
Thus this led to a lot of talking past each other, on all sides. The worst was the oft-quoted stat on police use of the registry. Since the debate was actually focused on what the registry symbolized, and whether we should have such a symbol, all such data completely missed the point. Unless you thought it was a powerful symbol, in which case anything which shows its social influence would matter.