- RadioNZ: "Joyce still not convinced about lower alcohol limit"
RadioNZ reports that Minister of Transport, Steven Joyce, says "more evidence is needed before the Government will consider lowering the general drink-driving limit". Others such have David Farrar have echoed the claim that specific evidence is needed that lowering the drink drive limit will have an instrumental effect on the number of road deaths and accidents.
Yes, changes to laws should be justified. But, no, the justification need not be specific evidence.
Both Joyce and Farrar are ignoring the precautionary principle. In general terms, this principle says that, in relation to risky activities where there is scientific or empirical doubt about the nature and extent of the risk, policy- and law-makers should favour the course of action which avoids the risk. That is, in the face of uncertainty, the burden shifts to those undertaking the risky activity to demonstrate it is not harmful. This principle is especially common-place in areas such as public health and environmental law; for example, it is specifically recognised in s 32(4)(b) of the Resource Management Act 1991.
So, we know that drink driving is a risky activity. That's why we prohibit driving above the current blood-alcohol level (80mg). If there's doubt about whether driving while above a reduced limit of 50mg (which I not sure there is doubt about when looking at international practice), then the precautionary principle would favour lowering the limit anyway and collecting data to demonstrate it is not risky or has no instrumental influence on road accidents and deaths - not the other way around!
Ultimately, these things involve a cost-benefit calculus. There are seldom king-hits in law- and policy-making. A balance must be drawn.
Joyce and Farrar et al are, however, underplaying the benefit (risks avoided) of lowering the limit by proclaiming uncertainty about their nature and extent. In this context, though, we're entitled to assume there is a risk associated with driving with a blood-alcohol of over 50mg, unless evidence shows otherwise. This means, for the purpose of the cost-benefit calculus, we can assume lowering the limit is beneficial
Of course, on the other side of the ledger, we can also say there is negligible cost associated with lowering the blood-alcohol limit. First, there is no social utility associated with driving having drunk that amount of alcohol. Secondly, a limit of 50mg still allows a buffer. It avoids criminalisation of behaviour which is not risky. Officials have confirmed that it will still allow folk to have a drink or two before driving without risking being over the limit.
This is a no-brainer. Our intuition tells us lowering the limit to 50mg is a sensible measure. It's supported by sound principle.