The last time Schleswig-Holstein was much in the news was in the 19th century when it was the center of a three-way tussle between Denmark, Prussia, and Austria, a diplomatic knot so complex that the British statesman Lord Palmerston said of it "The Schleswig-Holstein question is so complicated, only three men in Europe have ever understood it. One was Prince Albert, who is dead. The second was a German professor who became mad. I am the third and I have forgotten all about it."

But this northernmost German state came back into the news when Thilo Weichert, the state's privacy commissioner, raised an issue of such complexity that it will make the first Schleswig-Holstein question look like a dot-to-dot coloring book in comparison.

This month Mr. Weigert wrote to Facebook threatening to fine the social media company for failing to allow the state's citizens to use their service anonymously or pseudonymously, in breach of German law.

Facebook rejects Mr. Weigert's ruling, saying "We believe the orders are without merit, a waste of German taxpayers' money and we will fight it vigorously." But this dispute is more than simply another "European country angry at big U.S. company" story. This cuts right to the heart of a long-standing Internet debate—do we have the right to be anonymous online?

This has serious consequences in the real world. The Irish parliament is investigating the role of social media in a public debate following the suicide of Irish politician Shane McEntee after a campaign of abuse, some of it on social media. Furthermore, a recent study by researchers at the University of Wisconsin-Madison found that vituperative comments on science articles affected how people perceived the validity of the science. The less civil the accompanying comments, the more risk readers attributed to the research, a finding that has implications for the public understanding of science.