I was in favor of keeping Donald Trump’s name on the presidential ballot in California.

Until I went to Berlin this fall.

At a Saturday conference on German election law—if you haven’t noticed, your columnist is a democracy nerd—I met an entrepreneur named Gregor Hackmack. He’s so committed to democracy and participation that he launched a non-partisan online platform last year to enable dialogue between everyday people and elected representatives.

But now he’s organizing a petition to ban Germany’s second most popular political party—the far-right AfD, or Alternative for Democracy—from participating in elections.

Hackmack is wrestling with one of the hardest questions in democracy: When, if ever, can a democracy exclude anti-democratic politicians and parties from democratic elections?

The question is urgent because around the world democracy is threatened by authoritarian leaders who won office through democratic elections. Some of the world’s most oppressive governments—including those in Russia, Iran, Venezuela, Egypt, Turkey, and Tunisia—are led by men who came to power through voting.

It’s also a question now forced upon Americans by Trump’s return bid for the White House.

Blocking candidates or parties from elections doesn’t come naturally to democratically minded people. Nor should it—it’s a despot move. Autocracies and dictatorships routinely maintain and extend their power by blocking opposition figures from standing for office, such as when the Chinese government banned pro-democracy candidates in Hong Kong’s 2020 vote.

So why and how could we justify blocking candidates? One answer to that question, now getting attention in declining democracies, might be called the Democratic Self-Defense Exception: You should bar parties and politicians only when they threaten democracy itself.

The self-defense exception is the logic behind current legal efforts by pro-democracy nonprofits and some to remove Trump from 2024 ballots in most states.

It is also why it makes sense for people around the world to examine how Germany, where the Nazi party took power through elections, reckons with those who threaten its democracy.

In Germany, AfD is the political party that poses a danger to democracy—and society. AfD partisans and officials make threats against democratically elected officials. One party leader has expressed pride in Germany’s “World War II accomplishments.” The party embraces racist policies towards migrants, and pledges mass deportation and cancelation of citizenship for minority groups.

Yet since its founding in 2013, AfD has secured support from one-third of voters in economically-marginalized eastern parts of the country, and from 21% of respondents in national polls, the second-highest of any party.

Germans like Hackmack are arguing for banning the party because such racism and anti-migrant policies violate the German Basic Law, the country’s governing document, which was developed after World War II with the assistance of American political scientists. Specifically, AfD’s critics say the party aims to undermine the democratic order as expressed in Article 1 of the Basic Law, which calls human rights and human dignity “inviolable.”

They also point to Article 21, which specifically provides for banning parties determined to be “unconstitutional” because they do not “conform to democratic principles,” “seek to undermine or abolish the free democratic basic order” or “endanger the existence of the Federal Republic of Germany.” Germany’s federal constitutional court gets the final say on banning a party.

To those who suggest that banning AfD would only make it more violent and dangerous to democracy, supporters of the ban respond emphatically. They state that Germans’ expectation of heightened violence is itself reason to keep the party off the ballot: “The democratic process is undermined if it takes place permanently under the sword of Damocles, that a group with real power options wants to torpedo precisely this process,” wrote the constitutional law expert Klaus Ferdinand Gärditz in support of the ban.

To those who suggest that banning the party is a political question best left to voters in future elections, German Institute of Human Rights director Beate Rudolf, a ban supporter, writes: “German history in particular has shown that the free democratic basic order of a state can be destroyed if positions of contempt for humanity do not meet with energetic opposition in good time and are thus able to spread and gain acceptance.”

Hackmack and other supporters—including members of the country’s center-right party, the Christian Democratic Union—have gathered more than 400,000 signatures on a petition demanding the parties and national parliament ask the constitutional court to ban the party. A TV comedy show has joined the drive. Still, it’s unclear whether the petition will succeed; it’s been decades since the court banned a party.

Here in the U.S., Trump represents one pressing threat to democracy. The former president led an insurrection after losing the 2020 election, and has announced plans for a second presidency that sounds like dictatorship, including mass firings of civil service workers and prosecutions and even executions of Trump’s political opponents (whom he calls “vermin”).

Seeing how Germans are re-examining the Basic Law because of AfD’s threat to their democracy, I understood better why Americans are rereading the U.S. Constitution because of Trump’s threat here. Various interest groups and voters have filed suits in 28 states seeking to bar the former president from primary ballots. Trump’s conservative critics, including law professors and judges, are pushing hardest to boot him from the ballot.

“A president who tried to use force and fraud to stay in power after losing an election should not be allowed to wield the power of office ever again,” writes George Mason law professor Ilya Somin. “And we need not and should not rely on the democratic process alone to combat such dangers.”

The legal grounds for the ban efforts come from Section 3 of the 14th Amendment, which excludes from future office any person who has taken an oath to support the constitution and then rebelled against it, either through insurrection or by giving “aid and comfort” to the constitution’s enemies. Trump’s actions—his efforts to overturn the election, the January 6 insurrection, and his ongoing promises to violate the Constitution if he returns to office—all satisfy this criteria for ineligibility.

But these efforts have not been treated with the same seriousness that Germany gives its anti-democratic threats. The litigation hasn’t gotten much traction in the courts, or political support, even from Trump critics. As a practical matter, Trump’s eligibility will likely be decided by the courts; so far, no judge has been willing to bar him (with one jurist ducking the question with a dubious technical ruling).

In California, state officials—Secretary of State Shirley Weber, Attorney General Rob Bonta, and Gov. Gavin Newsom—have also taken no visible steps to block him from the March 2024 ballot before a December 28 deadline. That’s especially maddening because Trump has attacked California democracy, ever since his 2016 defeat in the state, with lies that our elections are “rigged.”

Trump has claimed that efforts to remove him are themselves an attack on democracy. In this gaslighting, he embodies the definition of “hypocrite” given by the first Republican president, Abraham Lincoln: “The man who murdered his parents, and then pleaded for mercy on the grounds that he was an orphan.”

Trump also argues, falsely, that taking him off the ballot violates his rights of voting or free speech. But democracy grants no inherent right to be president. What citizens of democracies instead have—as I was reminded in Berlin—is a responsibility to protect democracy, even when it means excluding those who won’t abide by its rules.