Clemm and others say German law makes it impossible to prosecute some sex offenders. The main problem, they say, is that the country's criminal code considers a person a victim if he or she tried to defend themselves. "Hence, the right of sexual self-determination is only protected if one defends it," said Clemm, who represents a faction of lawyers who are urging reforms.
For instance, if a woman is assaulted but does not try to defend herself, courts would be unable to find the offender guilty, according to Clemm. "If a victim only cries or shouts -- but does not physically defend her- or himself -- forcing someone to have involuntary sex is not illegal," Clemm said.
There are some exceptions to that rule: Assaulting someone who is sleeping or who has lost consciousness is always punishable.
Authorities say that there are as many as 160,000 rape cases in the country each year, but that only 1,000 end with a guilty verdict.
Other experts have been more cautious in interpreting the law that way. German lawyer Joachim Renzikowski said that the crime code was much more ambiguous than described by some. However, he agreed that there were certain loopholes that needed to be closed.
German legislation lags behind other countries: In most developed countries, "no" means no. Some countries even criminalize sex if someone has not deliberately agreed to it beforehand.
The European Union -- of which Germany is a member state -- requires countries to punish any involuntary sexual acts. Germany, though, has not yet ratified that convention.
The country's authorities have said that they are aware of possible loopholes in the country's sex crime code, and the justice ministry recently proposed amendments that would make it possible for courts to punish surprise attacks, for instance.
Many victims in Cologne were overwhelmed by their attackers and had very little time or no time to defend themselves. So far, 58 men have been arrested in those attacks.
Clemm said there were many other situations in which German law fails the victims: For example, having sex with someone who is in the process of waking up and does not actively and physically defend him or herself would be legal. Pressuring someone into having sex (without threatening physical violence) could also be legal in some cases.