An ex-magistrate who says he was forced to resign because he would not place children for adoption with gay couples has begun an appeal.
Andrew McClintock said he was concerned about children's welfare
Andrew McClintock, 63, of Sheffield, said he was discriminated against for his Christian beliefs.
The appeal has heard Mr McClintock believed children were best placed with heterosexual parents and gay adoption was an "experiment in social science".
His appeal follows an employment tribunal ruling in March.
The father-of-four, a member of the Christian People's Alliance council, had served as a magistrate in the family courts in Sheffield for 15 years where he decided whether children needed to be taken from troubled families and put into care.
Earlier, Paul Diamond, for Mr McClintock, told the London hearing that his client was the victim of indirect discrimination.
Child's best interests
Mr Diamond said his client believed he had "rational grounds" to question whether it was in a child's best interests to be adopted by a gay couple.
He said if there was evidence that a child would suffer, for example from bullying, then it would not be right to place them with a gay couple.
The hearing was told Mr McClintock wrote to his employers in the build-up to the change in law that allowed gay couples to adopt.
He requested permission to excuse himself from same sex hearings but his request was refused and he resigned.
Mr Diamond said: "He simply said.... in my view the best interests of a child are best served by a dual gender upbringing."
Adrian Lynch, for the Department for Constitutional Affairs, said the tribunal found his client's treatment of Mr McClintock was "justified".
He said it was for parliament to set the parameters for who can adopt children.
The hearing continues.