DW: Germany's Federal Constitutional Court has once again had to intervene concerning rights involving same-sex unions. Why?

Sabine Berghahn: In 2001, the Social Democrats-Greens coalition government granted civil partnerships to same-sex couples, against the will of the Christian Democrats (CDU) party, and its Bavarian sister, the CSU. When that government came to an end in 2005, other equality measures - such as in tax and adoption laws - could no longer be pushed through. There was not a majority because the CDU/CSU put up so much resistance. The liberal FDP party would have agreed to changes in equality laws.

But anti-discrimination developments in Europe overran the CDU/CSU. And the results could not be stopped, even by legislative blockades and alleged reforms. That's why the Constitutional Court had to jump in - in places where certain rights were not granted, even though married couples were entitled to them.

Who is really pulling the ropes in the CDU/CSU parties in this regard?

I would imagine that many in the CSU put the brakes on things because they still have a conservative image of what a family is supposed to be. Marriage and family go hand-in-hand for them. They may tolerate heterosexual, unmarried couples even when they have children together - but they aren't suppose to enjoy the same privileges as married couples. The same is true for same-sex partnerships. A change would mean a complete change of mentality and thinking, and would call into question the symbolic order of the preeminence of the marriage-and-family model.

And in the CDU?

Supporters of this model can also be found in the CDU. There was already a lot of resistance within the party when [then minister for family affairs] Ursula von der Leyen introduced changes to the parental allowance scheme and increased the amount of daycare facilities. This was a very contentious issue within the party. Angela Merkel is now probably thinking that if she allows putting homosexual couples on an equal footing with straight couples, she will cause conflicts within her own ranks. This in turn may have a negative effect on certain voter circles in the coming federal election.

This is why a decision was made at the party congress to keep things the way they are and wait for the court's decision first. It was clear to everyone that the outcome would be what it is, because the Constitutional Court had already chosen the path of consistency in the matter of equality and it had also chosen to follow antidiscrimination principles.

What comes next? Joint tax assessments for unmarried couples and people simply sharing an apartment? Has the ruling caused a new type of imbalance that needs to be rectified?

One can well imagine that this would be the next step - that people in these kinds of living arrangements demand changes based on the principle of equality. And that the Constitutional Court may even grant them such rights. This kind of step-by-step approach is fully legitimate and logical. Non-discrimination means restructuring the legal and social system in a way that abolishes long-established forms of discrimination. There is a clear connection between tax law - in this case joint tax assessments - and social rights.

Joint tax assessments were introduced to make it easier for the family's main breadwinner to support their spouse and children. Later, a principle of being able to support one's partner during periods of unemployment or in other adverse circumstances was extended to cover unmarried couples. When it came to the responsibilities of marriage, unmarried couples were placed on an equal footing, but at the same time the authorities were unwilling to extend the privileges of marriage to them.

Could the Constitutional Court's decision be a starting point for further tax reforms?

Registered same-sex partnerships have already gotten the ball rolling. It is a chance to show that things aren't just and can't continue the way they are. If this change is now made, it will also force the question whether joint tax assessments should be done away with altogether in favor of individualized taxation. This has already happened in most European countries - and these countries are usually also better at integrating women into the workforce.

Sabine Berghahn is a professor for law and political science at the University of Münster. Her work focuses on women's issues, gender politics and constitutional law.