One of the parents, Christer Johansson, says to Radio Sweden that even four years on he is still in shock. He was moving abroad to India in 2009 when Swedish police came on the plane and took his child.
Christer's wife, Annie, is from India, although they lived for the first seven years of their son's life on the island of Gotland.
The Swedish authorities say it is important for the community, and for democracy, that all children get a proper education and go to school.
Emma Östling is a legal expert at the Swedish National Agency for Education. She says there are exceptions for children who for some reason cannot get to a school, but since the new law came into effect in 2011 there is no way for parents who simply want to home educate to be allowed to keep their child and teach themselves.
She says if parents do not send their child to school the local municipality can start to fine the family. They will have to pay a sum based on their income; it has to be a significant amount.
But the police do not come and take children who do not go to school. Emma Östling says this stopped in the 1980s.
So there has to be a bigger issue for the local authority to justify taking a child away. This means that the local municipality's social department must have decided that the familiy's home was not a safe place for the child.
Christer Johansson completely disagrees. "They guess a lot of things. They build a character on you, but because it's not true. At the beginning there was an anonymous letter that said all sorts of things, but we cleared all of that up."
He says that social services had concerns about his mental health, and kept on calling him mentally ill even after he was cleared by a psychiatric evaluation.
Christer says some of his family's choices have marked them out as outsiders. He says they want to give their boy "a more natural medicine", and chose home schooling to spend more time with the child.
"We didn't do anything illegal, but we made choices that others don't make."
But on one visit to the foster family Christer Johansson took his child and drove away with him. He says to Radio Sweden he just lost control over himself.
The Gotland municipality say they are not talking about this case. They rarely speak about individual cases and they say all the documents are with the court. And the media in Gotland have also stayed away from this case. Both local radio and newspaper say to Radio Sweden that they think it is hard to judge what is happening in this case, because so many of the documents are still secret.