In 2013, Dirk and Petra Wunderlich decided to home-school their children even though it is against the law. They say they'd rather not have strangers teach their four kids and believe as Christians parenting should mirror that of God the father and Jesus.
They say during that first lesson, around 20 German authorities violently snatched their kids from their home.
Dirk Wunderlich described it as a traumatic event.
He said: "Our family life... why should it be disturbed for 4, 5, 6 hours a day? We want to be together and want to do our things for the whole day. There's no reason for our children to go into school which they do not like."
They went through a series of exams to test their academic levels while they were in custody.
Michael Donelly, from the Home School Legal Defense Association said: "The authorities took the children, tested them and found that they were doing fine and were very well-developed.
"Authorities said they were above average in their education attainment and returned the children. We filed a lawsuit to vindicate the family's rights".
When the Wunderlichs were released they were forced to go to school for 8 months. Their father explains it as a horrible experience for their children.
He said: "When the children went for eight months into school, they hated this time and they had no time for their hobbies. It was eight months lost."
ADF International says Germany is one 47 countries that abide by an international human rights agreement that protects the right of parents to direct the education of their children.
Lorcan Price, Legal Counsel for ADF International, believes this ban is a direct violation of that.
He said: "Germany is a signatory to Article 2 of Protocol 1 to the European Convention of Human Rights which holds that parents have a prior right in relation to the direction of the education of their children. "
He added: "So it's crucially important to the court to develop that concept and that obligation, holding clearly what it means in practice for governments in relation to allowing their citizens, in a human rights context, to be able to direct the education of their children. It's pretty clear that would involve providing education in the home place".
The Home Schooling Defense Association states Germany's reason for its strict ban on home-schooling is due to its efforts to discourage parallel societies from forming. The German government also believes that minorities should integrate in society and a major way of doing that is through schooling.
Donelly claims that has not proven to be true.
He said: "That's what they say. Of course when you look around the rest of the world and see how home-schooling moments are flourishing, you don't see any problems with socialisation. You don't see any problems with parallel societies. Home schoolers do not create parallel societies. They're just parents who want to do best for their kids and Germany is among a very few nations that are very hostile to parents who want to home-school their children".
This is not the first time home-schooling has been challenged. There was a case 10 years ago where the European Court ruled in Germany's favour saying parents cannot home-school their kids based on religious or philosophical reasons.
However, Wunderlich says because German police took his children away in such a hostile way in 2013, he's hopeful the judge can see the violation that occurred.
Wunderlich said: "If today is the day when the court decides okay, it was a big violation of human rights I will be very enthusiastic."