The lawyer arguing for Austria pointed out to the ECHR that most European countries do not allow a child to have two mothers or two fathers. She argued that this is relevant to the leeway given to each country (called the "margin of appreciation") in implementing the European Convention on Human Rights provisions on respect for family life.
The petitioners are represented by Helmut Graupner, leading Austrian gay rights attorney. He noted that the Youth Welfare Office found that it would be in the child's best interest for the mother's partner to have legal custody of the child but that this was not permitted under the law. Graupner quoted to the court the opinions of numerous experts on the well-being of children raised by same-sex couples.
Although Europe was way ahead of the US in recognizing same-sex couple relationships, beginning with registered partnership in Denmark in 1989 and same-sex marriage in the Netherlands in 2001, European countries have actually lagged behind the US in recognition of parentage for same-sex couples. It is a relatively recent development that some countries do allow second-parent adoption or parentage for the same-sex partner of a woman who bears a child through donor insemination. Austria not allows same-sex couples to enter registered partnerships, but the law explicitly bans second-parent adoption for registered partners.