The case concerns family reunification. According to the CJEU Press release no. 95/20:

In 2012, B. M. M., who has refugee status in Belgium, submitted applications for residence permits by way of family reunification for his three minor children at the Belgian embassy in Conakry (Guinea). Those applications were rejected. In 2013, B. M. M. submitted further similar applications at the Belgian embassy in Dakar (Senegal). In 2014, the competent Belgian authorities rejected those applications on the ground that they were based on fraudulent and misleading information. Hearing actions against those decisions, on 25 April 2014, the Conseil du contentieux des étrangers (Council for asylum and immigration proceedings, Belgium) declared them inadmissible on 31 January 2018 on the ground of lack of interest in bringing proceedings. According to settled national case-law, the interest in bringing proceedings must exist when an action is brought and continue to exist throughout the proceedings. In the present case, even taking into account the dates of birth set out in the applications, the children concerned had all become adults on the date of delivery of the decision of the Council for asylum and immigration proceedings and therefore no longer satisfied the conditions laid down by the provisions governing family reunification which minor children are entitled to enjoy.

The three children concerned lodged an appeal on a point of law before the Conseil d’État (Council of State, Belgium). According to them, the interpretation of the Council for asylum and immigration proceedings, first, disregarded the principle of effectiveness of EU law, in so far as it prevents them from enjoying the right to family reunification guaranteed by the relevant directive and, secondly, infringes the right to an effective remedy. In that context, the Council of State decided to refer questions to the Court of Justice for a preliminary ruling.

The CJEU held that the date which should be referred to in order to determine whether a ‘minor child’ is concerned is that of the submission of the application for entry and residence for the purposes of family reunification, and not the date on which a decision was given on that application by the competent authorities of that Member State, as the case may be, after an action against the decision rejecting such an application.

The CJEU also held that the action against the rejection of an application for family reunification of a minor child cannot be held inadmissible on the sole ground that the child has reached majority during the court proceedings.