Criminal lawyers dealing with cross-border offences will have to become familiar with a new directive. Eventually.

You may have thought that the recent Google judgement by the European Court of Justice was its one bold judicial act of the year. But now the court has - for the second time in a month - struck down an EU directive. There must be something new and powerful in the water in Luxembourg.

Last month, it struck down the data retention directive (2006/24/EC), and this month it has struck down the directive on cross-border exchange of information on road safety related traffic offences (2011/82/EU). This is potentially of importance to the UK and to solicitors who undertake road traffic offences work, as I shall explain. But first I will outline the background.

The two cases - of data retention and road traffic offences - are very different, not only in content obviously, but in the reasons for, and therefore consequences of, their annulment. The data retention directive was annulled because it caused serious interference in the fundamental rights of respect for private life and of the protection of personal data, without that interference being limited to what is strictly necessary. It was annulled completely. The road traffic offences directive, on the other hand, was also annulled, but on the grounds that its legal basis was wrong.

However, crucially, the directive has been maintained in force (unlike the data retention directive) for a year to allow it to be re-introduced on the correct legal basis.

Legal basis? That sounds something unimportant. But in fact, it is the legal basis which causes the difference for the UK. The history is this. The European Commission introduced the directive in the first place on the legal basis of Article 91 of the TFEU (road safety). The Council, eventually supported by a reluctant parliament - which wanted to bring the matter to an end after three years of negotiation - passed it on the basis of Article 87 TFEU (police co-operation). The Commission then took the matter to court.

You may wonder what difference this makes, particularly to the UK.

Well, the UK has an opt-out from Article 87 (police co-operation), and so the directive has not so far applied to the UK. You will not be surprised to learn that the UK intervened in the case - along with a few others, it must be said - to argue that Article 87 was the correct legal basis after all. But now that Article 87 has been shown to be wrong, and the directive is going to be re-introduced on the correct basis (presumably Article 91 – road safety, from which the UK does not have an opt-out), all you criminal lawyers dealing with cross-border traffic offences are going to have to bone up on the new directive when it is re-issued.

So what does the annulled directive do? It sets up a procedure for the exchange of information between member states in relation to eight road traffic offences (speeding, non-use of a seat-belt, failing to stop at a red traffic light, drink-driving, driving under the influence of drugs, failing to wear a crash helmet, use of a forbidden lane and illegally using a mobile telephone). The member states can access each other’s national data on vehicle registration in order to determine the person liable for the offence.

However, it is not as far-reaching as the Commission originally wanted. In particular, the current directive has no provisions on what should be done if the offender simply decides to ignore orders for payment. But a new legal basis could change that. When the member states altered the legal basis during the adoption process, they also threw out a section dealing with legal proceedings for infractions and possible sanctions.

As a result, the current directive does not guarantee sanctions, but only mutual access to vehicle registration data.

It is unlikely that the Commission will introduce controversial new measures now to address this gap in the new directive, since it would probably not then pass in the 12 months allowed. But we should expect such measures in the future, now that the legal basis has been settled. And those new measures will apply to UK drivers elsewhere in the EU, and to EU drivers in the UK.

There will doubtless be a battle over the future measures. One of the reasons for the Council throwing out the previous legal basis was that member states did not want police forces other than their own to have powers to enforce punishments. They feared it would lead to a harmonisation of road traffic law. (Nevertheless, there is a problem to be tackled, since apparently 5% of drivers on EU roads are from another member state, but they account for 15% of traffic offences.)

You see what excitement the EU brings us? If Scotland votes for independence, and we then vote to leave the EU, we will die of boredom on our own.

Jonathan Goldsmith is secretary general of the Council of Bars and Law Societies of Europe, which represents around a million European lawyers through its member bars and law societies. He blogs weekly for the Gazette on European affairs