Far-right forces have made sweeping gains in a German state election. The nature of a country that has respected diversity and built a free and open society is being called into question.

The far-right Alternative for Germany, or AfD, won a landslide victory in the state parliamentary election in the eastern state of Saxony-Anhalt, securing 43.8% of the vote. The possibility that the party could take control of the state government has arisen.

The AfD has expanded its support by calling for the deportation of undocumented migrants and tighter immigration controls. Elements of extreme nationalism that refuses to recognize even citizens of the country as German if they have immigrant roots have also been seen in some parts of the party.

In Germany's federal system, states hold strong authority across a wide range of areas, including policing and education. If the AfD takes control of a state government, the exclusion of immigrants is certain to advance.

The party also advocates a shift away from history education emphasizing reflection on the Nazi era, raising fears that the principles defining postwar Germany could be eroded.

Germany, reflecting on the fact that the Nazis built a dictatorship through elections under the Weimar Constitution, has accepted placing certain restrictions on the activities of forces that threaten human dignity and democracy. This approach is known as "defensive democracy."

Germany's Constitution, the Basic Law for the Federal Republic of Germany, therefore provides for measures including the prohibition of unconstitutional political parties. Neo-Nazi parties and the Communist Party of Germany have previously been banned or dissolved. The AfD's Saxony-Anhalt branch itself has been recognized as a far-right extremist organization by the state's domestic intelligence agency and placed under surveillance.

That same party has now won considerable support in a democratic election. The Federal Constitutional Court can put the brakes on behavior that violates the Constitution, but if such forces continue to grow, there is also a risk that even the court could fall under their influence. Defensive democracy is facing a moment of truth.

The AfD initially extended its support in what was once East Germany, backed by discontent over issues including the economic disparity that remained even after the country's unification in 1990.

Criticism that established parties have failed to resolve issues surrounding immigration and the economy is spreading across Germany. The AfD also now leads nationwide party support ratings. Other parties have been unable to ignore this situation and are competing to adopt tougher immigration policies.

Even so, drifting easily into exclusionism will not provide a solution. Rather, it will only deepen divisions and destabilize society. Germany must protect the universal values it has nurtured since the end of the war.