In response to a query about a challenge to Germany’s electoral law, Espen Bjerke has the following reply. (All of what follows is from Espen.)
It seems the deadline to fix the problem of “negative vote-values” will be missed, meaning that Germany will be without a valid electoral law starting 1 July. The deadline was imposed by the Constitutional Court three years ago when it ruled against that inherent paradox.
From what I just read it seems the problem is that the CDU wants to keep its current advantage but has been unable to come up with changes that would be constitutional as well as practical. The coalition parties say they will introduce something after the summer break, so that this rather Merkelian disarray is ended.
For those who read some German, wahlrecht.de is probably the best source on this, especially since they were among those who brought the suit in the first place.