Protection of family diversity: marriage, civil and de facto unions (cohabitation, joined families); same-sex unions and / or marriage

LPartG denied registered civil partners the possibility of also adopting their partner's adopted child (so-called successive adoption), whereas § 1742 of the Civil Code opened up the possibility of successive adoption to married partners and § 9.7 LPartG enabled the adoption of the registered civil partner's natural child (so-called stepchild adoption). The constitutional complaint concerned the question of whether this provision is compatible with the Basic Law.
The constitutional complaint was based on two adoption proceedings in which the complainant wished to adopt the adopted child of his registered civil partner. The civil partner had previously legally adopted a child born in Bulgaria and Romania respectively and subsequently established the registered civil partnership. Both partners lived with the child in a common household. The adoption application was rejected by the local court. The same happened regarding the appeal filed with the regional court. While the higher regional court also rejected the complaint, in the opinion of another higher regional court there was a violation of § 9.7 Civil Partnership Act against Article 3.1 of the Basic Law insofar as it did not allow successive adoption by the civil partner. The proceedings were suspended to this extent and the question was submitted to the FCC for a decision. 
The FCC held that the exclusion of successive adoption by registered civil partners did not initially constitute a violation of the child's right to state guarantee of parental care and upbringing, of the fundamental parental right or of the fundamental family right. The children concerned have a parent in the legal sense and, with the civil partner, a person who, under the Civil Partnership Act, can also perform certain parental tasks without assuming parental responsibility in the legal sense. This sufficiently satisfies the state's duty to protect the child arising from Article 2.1 in conjunction with Article 6.2 Sentence 1 of the Basic Law. Although the parental right under Article 6.2 Sentence 1 of the Basic Law also protects same-sex parents, the holder of the right can only be someone who has a biological or legal parental relationship to the child.
However, the non-admission of the successive adoption of adopted children of registered civil partners by the other civil partner while at the same time permitting successive adoption by spouses under § 1742 of the Civil Code and the stepchild adoption provided for by § 9.7 of the Civil Partnership Act violateed both the children concerned and the civil partners concerned in their right to equal treatment under Article 3.1 of the Basic Law. Within the framework of the examination of the violation of fundamental rights, a significantly stricter standard of review is applied compared to the mere prohibition of arbitrariness, since essential fundamental rights are affected.
The restriction of successive adoptions outside marital relations pursues first the aim of not exposing the child concerned to competing and contradictorily exercised parental rights and of preventing its transmission from family to family. In view of this, however, the permanent and binding registered civil partnership does not differ from marriage in any justifiable way. According to the assessment of experts, successive adoption is also suitable for developing stabilizing developmental-psychological effects regarding the best interests of the child. 
The exclusion of successive adoption was not justified by the purpose of preventing circumvention of joint adoption by registered civil partners, which is not permitted by the legislature, since the two forms of adoption differ from each other, at least in their procedure. Nor was a sufficiently weighty factual reason apparent that justified the favorable treatment compared to comparable forms of life, which is in principle permissible regarding the special protection of marriage enshrined in Article 6.1 of the Basic Law.