It has been repeatedly argued that the prolongation of the Article 50 deadline for a “long" period period beyond March 29 (in order to seek a sensible solution to Brexit) is not possible because it would oblige the UK to participate in the May 26 European elections and that this participation would admittedly create a confusing situation.
In other words, does the occurence of these elections prevent a “long" (ie 12 month) extension of the article 70 deadline in the UK ? More precisely, would the fact that the UK might still be a member of the EU by that date oblige this country to hold full fledged european elections at this date ?
Probably not - for both reasons of common sense and legal arguments.
Common sense
If/when exceptionnal political or constitutional circumstances prevent a member State from holding european elections at the offficial date, this should neither impeach the general vote in the EU nor create a situation of no representation of this State in the EP during the period considered. Would the problem affect a member State less emblematic than the UK (ie. Malta, Estonia, ...), this assertion would not even be contested and a pragmatic solution would be found without much difficulty or publicity. Moreover, when considering the overwhelming importance to reach a reasonable and lasting solution to the strategic UK problem, such a common sense consideration should prevail.
Legal arguments
Two measures at least might be considered to solve the problem :
either a simple prolongation of the mandate of previously elected UK representatives for the agreed period,
or the provisionnal representation of the UK delegation by members of the British Parliament elected/nominated by their peers.
The first solution would probably be the most simple and secure one. It would require a formal and parallel decision by both the Council and the UK constitutional authorities - as well as a formal agreement between them. Such agreement could be entered in the common decision to prolong the two years article 50 deadline.
There is no specific provision in the Treaties that would impair the extension of the mandate of present UK MEPS - and it is not clear that this extension would entail a violation of any fundamental democratic principles or rules (1).
Actually, several legal arguments have been presented in favor of this interpretation of EU law, most recently by a member of the ECJ writing on a personal basis (2).
It has been reported that the legal services of the Council (and/or the Commission's) might be opposed to this interpretation of EU law. This is not confirmed at this stage and should not, in any case, be considered as an absolute obstacle (3).
In summary, the occurence of EP elections should not stand in the way of an eventual prolongation of Brexit negotiations - prolongations that might lead to a new “popular vote” (ie referendum) on the issue. If such a vote would entail a withdrawal of the UK decison to leave the EU, formal elections of new british MEPs would of course have to be organized as soon as possible.
Jean-Guy Giraud 19 - 03 - 2019
(1) The issue of the actual total number MEPs (under the new system of repartition) would have to be provisionnaly settled in accordance with relevant Treaty articles and other EU regulations.
(2) see the article from Mrs Eleanor Sharpston, ECJ Advocate General :
See also : https://acelg.blogactiv.eu/2019/03/14/the-complications-of-a-brexit-delay-that-runs-into-the-european-parliament-elections-by-leonard-besselink-and-bastian-michel/
(3) The legal advices of both services were recently contadicted by the ECJ in the case concerning the unilateral withdrawal of an Article 50 decision by a member state : https://curia.europa.eu/jcms/upload/docs/application/pdf/2018-12/cp180191fr.pdf