The law-makers' fallacy

There’s a connection between the demand to criminalize mephedrone and Tim Loughton’s call to prosecute more teenagers for having sex.
Both fail to see what the law does. The law does not ban things - at least not directly - but rather changes incentives. And these changes might not have wholly desirable effects.
A law against selling mephedrone, in effect, raises the costs of supplying it - as these costs would now include the probability of a prison sentence. Some suppliers might respond by dropping out of the business. This would have the effect of raising the price of mephedrone, which in turn would tend to reduce demand. However, this mightn’t be a wholly good thing. Some consumers would switch towards other drugs, which become relatively cheaper, so the profits of cocaine dealers go up. That would attract more people into that business.
Also, not all mephedrone dealers would drop out of the market. Others would take steps to increase the profits of their business, to compensate for the higher risks. This could mean that they mix the drug with other substances to make it go further. This is turn would increase the health risks faced by users. And/or it could mean that they take greater efforts to become a monopoly supplier, so gang wars break out as dealers use violence to drive out rivals.
Criminalizing teen sex works similarly - it raises the costs of supplying it. At the margin, this will discourage some girls from supplying it.  But this could have the effect of causing more date rape, as frustrated teenage boys force themselves upon girls.
And in both cases, we’d end up with some young people having criminal records who otherwise wouldn’t. This would worsen their labour market prospects, which in turn would lead some to commit crime; it is trivially true that lower returns to lawful work increase people’s incentives to undertake illegal effort.
Now, I am not saying that adverse effects such as these more than offset the proposed benefits of such laws. That’s an empirical issue, which depends upon the elasticities involved. All I’m saying is that the “ban it” attitude is just unscientific.
I guess that many of you - having an economist’s mentality - think what I’ve said is just trivial, and can probably think of more possible adverse effects yourselves. But there’s another question here: why do so many people not share our attitude?
Partly, I think, there’s a mixture of egocentric bias and wishful thinking, which leads people to believe they can bend others to do their will.
But there might also be a selection effect. MPs, from any party, are selected for an excessive faith in the power of law; you are more likely to want to spend your career making laws if you think the law can be used to manage society for the better. In this sense, there is an innate bias amongst politicians to underweight the fact that laws have unforeseeable and perhaps adverse effects.

Comments

[Trevor Brown]

Why should MPs be any less thoughtfull or intelligent or rational than bloggers?

Crys for laws to be changed and things to be banned are not taken up because they will work, it is because many peopled are not intelligent and rational, in fact many are stupid - but all have the vote.

And there are more of them than us, whatever we think, if we wanted to get elected we would have to pretend to also support crass ideas.

The challenge for the ineffectual minority of insightfull intelligentistas, is how to communicate with the lumpen stupidistas, rather than endlessly and ineffectually deride them and their stupidity.

The real challenge is how to harness the stupid vote to serve the objectives of the rational tendancy!

Well?

[Trevor Brown]

ps how dies this stupidista edit the myriad typos from his post above?

[John Terry's Mum]

The thought of young, attractive people exploring sex together fills me with a nostalgic kind of jealousy.

Of course they should all be locked up.

[patrick]

I'm not entirely convinced that criminalising (or more to the point enforcing the existing law on) teenage sex would have the effect of increasing date rape, not least because I would hope that the criminal justice system would continue to take a rather harder line on rape than on consensual sexual activity between teenagers.

That's not to say it would be a good idea, though. One risk might be that teenagers take greater steps to avoid doing anything that might draw attention to what they are up to - like obtaining contraceptives or sexual health treatment. I doubt that people providing such services would report children to the police for approaching them, but the 15 year old girl or boy might be less certain. All of which might mean that a tougher enforcement stance on underage sex could actually lead to an increase in underage pregnancies rather than a decrease.

As for the Mephredrone issue, I can't help but think that slowly criminalising, chemical compound by chemical compound, every legal industrial product which someone finds has mind-altering effects is a fool's errand.

[Julia Smith]

"Criminalizing teen sex... could have the effect of causing more date rape, as frustrated teenage boys force themselves upon girls."

I thought there was research somewhere to show that most rape doesn't happen because of frustration caused by a lack of sex.

The only link I could find regarding it was this and unfortunately it doesn't include any facts or figures: http://geshem.bi.org/patternsa.html

but it does include this quote: "...rape is not motivated by sexual desire nor is it fulfilling a need for sexual ratification. It is an act of violence motivated by anger, control and frustration--not sexual frustration."

That point aside, I think this is great and you are really on to something with this: "you are more likely to want to spend your career making laws if you think the law can be used to manage society for the better" - especially remembering that many of this crop of politicians are also lawyers, so likely to have a higher-than-average belief in the power of the law.

[Oranjd]

A lot of MPs are practising or former lawyers. Go figure.

[Paul]

You assume the lawmakers want to do good, rather than (for example) indulging in Santa Claus fantasies, or wanting to throw their weight around. While laws often do little good, they are just fine for these other ends.

[Big Fez]

"The law does not ban things - at least not directly - but rather changes incentives."

Is this really the only thing a law does? So the only reason not to commit a crime (say, armed robbery) is because the possibility of being caught and imprisoned outweighs the potential benefits? This might be true of homo economicus but I personally don't feel the need to do a cost/benefit analysis to decide whether or not to commit a crime.

Even without getting into the deeper complexities of the interaction between the law and people's morals there must surely be room for straightforward ways in which the law can influence behaviour. Perhaps effects like that from peer pressure (if something is illegal most people must think it is wrong) and laziness (I can't be bothered analysing every moral question so, as a rule of thumb, try to obey the law).

[Bruce]

My understanding is that mephedrone isn't such a great high that many would bother with if it were not legal. If you are messing with the legal risks of a Class A/B drug, you might as well use something better. So a ban might actually reduce use of mephedrone significantly, though probably have little impact on drug taking generally. That's not to detract from your broader point.

[Philip Walker]

"Is this really the only thing a law does? So the only reason not to commit a crime (say, armed robbery) is because the possibility of being caught and imprisoned outweighs the potential benefits? This might be true of homo economicus but I personally don't feel the need to do a cost/benefit analysis to decide whether or not to commit a crime."

Yes, but you have a conscience. Not everyone pays theirs much attention/was given such a clear understanding of right and wrong/has had the kind of upbringing you did/etc. As someone once put it, we know that law is not made for the righteous, but for lawbreakers and rebels.

The non-deterrent effects of law are basically the reason why this government has been legislatively hyperactive: it's not about deterrence, but simply about 'sending a message'.

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