A Sikh couple claim they were advised by an adoption agency not to apply because of their “cultural heritage”.
Sandeep and Reena Mander were told by Adopt Berkshire that white British or European applicants would be given preference as only white children were in need.
It is not illegal for adoption agencies to prioritise on the basis of race.
“They took the colour of our skin as the overriding reason not to progress with the application”, said Mr Mander.
A spokesman for Adopt Berkshire said: “We do not comment on ongoing court cases.”
The Royal Borough of Windsor and Maidenhead has not responded to a request for comment.
The couple contacted Adopt Berkshire, the official adoption agency for Windsor & Maidenhead Council, to look at adoption after several failed attempts at fertility treatment.
“We said that, having thought about it for six months, it was something that we really want to do,” Mr Mander told the BBC.
“I could tell on the phone it wasn’t going to end nicely.
“She asked what background we were from. I said we were from an Indian background, and she said that they were unable to prioritise us, and they wouldn’t look at our case.
“They said we should seek other means of adopting a child”.
Adoption agencies are allowed to prioritise on the basis of race in order to match children to prospective parents of the same ethnic background.
But the government has also said that a child’s ethnicity should not be a barrier to adoption.
Adopt Berkshire’s website says children in need of adoption “will reflect the racial, cultural and religious backgrounds of the populations within the areas from which they originate”.
It adds that the authority will seek prospective parents of a similar background to the child, though they would not keep children waiting to “achieve a direct match”.
“Although my cultural background is Indian, I don’t have any links with India, I’m a British person,” said Sandeep.
“We are a great couple, we’re happily married for ten years and financially stable, we have a five bedroom house with four spare bedrooms.
“We thought we would be able to at least get to an application stage”.
“Cultural heritage is important and should be looked at, but a number of factors should be looked at, and people shouldn’t be stopped from getting to the application stage because of one particular area”.
“We are angry and upset that this happens in this particular day and age, we know that we will be very good adopters”.
The Manders are applying to Slough county court, seeking a declaration that the policy should allow them to adopt.
Their case is supported by the Equality and Human Rights Commission (EHRC).
Sandeep and Reena have also decided to pursue adoption abroad, instead of locally.
“We are now looking at inter-country adoption, which is so costly”, added Reena.
“We want to raise awareness, we don’t want this to happen to other couples”.