According to EMN Ireland:

"The issue at the heart of this appeal was the extent or breadth of the definition of “child” for the purpose of refugee family reunification and whether that definition could include a minor who is not a biological or adopted child of the applicant. The High Court ([2019] IEHC 284) held that the term “child” in section 56(9) of the International Protection Act 2015 could include a non-biological child in light of the wide diversity of family structures."

"The Supreme Court held that the term “child” in section 56(9) of the International Protection Act 2015 can only be a reference to a biological or adopted child of the sponsor, as this was the literal and ordinary meaning of the term. This was reinforced by an examination of the historical background to the legislation, which made it clear that rather than introducing a broader meaning of the word “child” in the section, the overall effect of the section was restrictive in terms of those to whom family reunification could apply. This was a case in which a serious doubt arose as to the paternity of the two children in respect of whom the applicant sought family reunification. That serious doubt was created by the applicant himself in correspondence with the Minister. In those circumstances it was appropriate to seek DNA testing to establish the relationship between the applicant and the children concerned. In circumstances where he refused to undergo such testing, the Minister was entitled to draw an inference from that fact and to refuse the application."