From 5 December 2014, it became a criminal offence in Scotland to drive a motor vehicle with more than 0.05 per cent alcohol in the blood stream. This compared with the higher limit for the rest of the UK and for Scotland before that date, of 0.08 per cent. Most other European countries operate the lower limit of 0.05 per cent, or less.

In the early days of the new limit, there was a marked reduction in the number of prosecutions for drivers who had exceeded the previous limit of 0.08 per cent, but relatively few prosecutions for contravention of the new, lower, limit. Now, however, the numbers of prosecutions for the lower limit are increasing. If the new rules reduce the number of persons driving with dangerous levels of alcohol in their systems, then they are likely to be hailed as a success.

There are a number of difficulties, however, with that conclusion. In the first place, it is not clear that the object has been achieved. I have not seen any evidence that driving with more than 0.05 per cent alcohol but less than 0.08 per cent constitutes a danger. Apart, that is, from the knee-jerk and unsubstantiated reaction that any alcohol in the system constitutes a danger. In the second place, the simple reduction or even exclusion of targeted conduct cannot of itself justify the relative legislative intervention. In other words, the end does not justify the means. If it were otherwise then we would have no need for justice or proportionality. We would simply bring in harsh penalties, even capital punishment, to ensure that the end was achieved and the targeted conduct brought to an end. We accept, however, that the interests of justice and proportionality have to be observed and that is where I query the new legislation.

Is it proportionate, for example, to criminalise certain drivers who drive within a safe limit in order to discourage other drivers from exceeding that limit? Further, was any thought given to the adverse consequences to the individual of a drink-driving conviction before the threshold for such conviction was substantially reduced? These consequences already include a minimum of 12 months disqualification from driving and a substantial fine and possible imprisonment. Was any consideration given as to whether the same penalties should apply to the lesser degree of offending brought about by the new legislation? If the offending is lesser, should not the penalty be also lesser?

There are also substantial indirect consequences from conviction for drink driving. These may include loss of employment, even where driving is not directly relevant to the employment in question. Any person holding judicial office is relieved of that office on sustaining a drinks driving conviction. Should that consequence continue to apply where the level of offending is less than was previously the case? There has been a business-threatening decimation of responsible social drinking in some rural pubs. We do not know whether any of these factors were taken into account and, if so, what weight was given to them.

The new lower limit which now applies in Scotland appears to be in harmony with the limits which are applied in mainland Europe. However, any such harmonisation is superficial. Important and fundamental differences have not been taken into account. While other European states certainly apply the lower limit 0.05 per cent and some of them even lower than that, that is not by any means the whole story. The penalties in these countries are generally calibrated to the level of offending. These penalties may include a reduced or no disqualification from driving and reduced fines for breach of the 0.05 per cent level. No such calibration has been carried out in the changes which have been imposed in Scotland.

One hopes that political considerations did not drive the measure. However, the change was made at a time when separation from the rules applicable to the rest of the UK and which appeared to harmonise with Europe, ticked certain boxes. Again, the new measure appears to have been conceived during the dying days of office of a justice minister with a very uncertain future. Where legislation is driven by specific objectives, political or otherwise, without due regard to the interests of justice for all citizens, including law abiding drivers, then the operation of law and relations between police and public are likely to be degraded. One might conclude that this legislation was brought about far too hastily and that it has raised more questions than it has resolved.