Hamburg — FOR all its horror, what happened on New Year’s Eve in Cologne and other German cities might help the Germans solve a longstanding problem. The issue is not the one-million-plus refugees who have come to us in the first place. It is how to deal with problems that immigrants might be, are or will be causing.

More than 650 criminal complaints have been filed by women in Cologne regarding that night, and more than 150 in Hamburg, including two cases of rape. A 28-year-old women named Katia said: “Suddenly I felt a hand on my bum, on my breasts, I was grabbed everywhere, it was horrific. I was desperate, it was like running the gantlet. Over the space of 200 meters, I think I must have been touched about 100 times.” Of the 50 suspects identified in Cologne, the bulk are from northern Africa, mostly from Morocco.

These are uncomfortable facts. And until now, Germans have struggled to find an appropriate, decent way to address the issues they raise, without being labeled a Nazi or a fool. At last, this is changing. If Willkommenskultur, the welcoming culture, was the word of the year for 2015, this year’s leading candidate should be Ehrlichkeitskultur, the honesty culture. Cologne has been the catalyst: It shows that we must talk more frankly, yet not less responsibly, about immigration.

It is now up to Chancellor Angela Merkel to transform the new soberness into action. She has already made corrections to her open-door policy, including a stricter deportation law for immigrants who commit crimes. But she’ll have to do even more, and she’ll have to do it quickly.