Berlin record donation to CDU: Major donor Gröner must testify as a witness in court

Real estate entrepreneur Christoph Gröner donated 800,000 euros to the CDU. A lawsuit is now underway to determine whether the party must pay 2.4 million euros.

Christoph Gröner in front of the former postal savings bank at Möckernbrücke in Kreuzberg. As the district and Senate increasingly demanded more, the developer withdrew from the project to build luxury apartments there. Meanwhile, construction is underway at Möckernbrücke, where "die Macherei," a residential and commercial district, is being built. Charles Yunck/imago

The capital's administrative court sees a need for clarification in the dispute over a large donation of approximately €800,000 to the Berlin CDU in 2020. It will therefore hear the donor as a witness, as presiding judge Erna Xalter announced on Thursday.

It must be clarified what expectations real estate entrepreneur Christoph Gröner and his company had with the donation to the CDU in 2020. From the court's point of view, this is the only way to determine whether there has been a violation of the Party Law and whether the Bundestag administration should have imposed a sanction against the CDU.

Was Berlin’s record donation to the CDU legal?

This marks the first success of the lawsuit filed by satirist and MEP Martin Sonneborn's party. A spokesperson for Sonneborn described the court's ruling as a "partial victory." Sonneborn also responded: "We are already looking forward to the discussion with Mr. Gröner. We would also accept an 800,000 euro donation – but without any consideration."

Background: Sonneborn's party, Die PARTEI, sees a violation of equal opportunity. The proceedings are intended to compel the administration to classify the donation as illegal and impose sanctions on the CDU. The proposed payment would be double the amount—€1.6 million—plus the repayment of the €800,000 donation.

However, the Administrative Court does not yet consider a verdict possible. "The matter is not yet ready for a decision," said Judge Xalter. First, the businessman Gröner must be questioned. The court has scheduled August 28 as the hearing date for this.

Gröner and his company had transferred the sum to the Berlin CDU in 2020, before the 2021 parliamentary elections. Gröner's public statements had been interpreted as meaning he expected something in return. However, Gröner and current Governing Mayor Kai Wegner, who was already Berlin's CDU leader in 2020, had rejected the accusation of influence.

This could be expensive for the @CDU ... Smiley!

Many thanks to all donors who made this lawsuit possible - we have overcome the first hurdle... pic.twitter.com/uuqX4Zn79a

— Martin Sonneborn (@MartinSonneborn) May 22, 2025

In July 2023, the Bundestag administration responsible for reviewing party donations declared, following an investigation, that there had been no violation of the Party Law. A statement by the CDU had dispelled the suspicions raised in media reports, the statement stated.

It was a huge deal, the largest party donation since reunification: In 2020, at the start of the election campaign for the Bundestag and House of Representatives elections the following year, the Berlin CDU received a donation of €800,000, duly disclosed by the responsible Bundestag administration. The money came from real estate entrepreneur and project developer Christoph Gröner.

Questions immediately arose: Why was Gröner doing this? Did he want to contribute to democratic opinion-forming and therefore strengthen a party? But why only one party? So why would a multimillionaire real estate entrepreneur donate so much money to an opposition party? These questions initially remained unanswered, as political rivals suspected an attempt by the construction industry to exert influence .

Record donation in court: Does the CDU now have to pay a 2.4 million fine?

Back then, it wasn't until 2021, as the elections drew closer and the questions became more pressing, that those involved spoke out publicly. In May of that year, donor Gröner told Deutschlandfunk : "I set three conditions for the CDU." First, he wanted children with disabilities in children's homes to be better off. The second wish—critics called it a demand—concerned the Berlin rent cap, which at that time had not yet been rejected by the Federal Constitutional Court and which Gröner viewed critically. Third, he wanted "a level of communication" to be established on the topic of children's homes—"because we support 2,500 children in Berlin." In fact, Gröner was funding several charitable foundations at the time.

Record donation in court: What did the donor demand from the CDU?

Three months later, in the midst of the heated election campaign, it was Kai Wegner 's turn. In an interview for the "Young & Naive" series, the CDU's leading candidate spoke about the donations and related statements by Christoph Gröner: "He expressed a wish. He said to me: Mr. Wegner, please do everything you can to ensure that there aren't so many homeless people in the city."

Whether it's for the homeless, children in care homes, or rent control – legally, the supposed purpose of a party donation is irrelevant. But if these wishes, demands, or even conditions were actually communicated in connection with the donation, the donation would be illegal under the Party Donations Act. The CDU would not have accepted a so-called influence donation, and the Bundestag administration would not have been allowed to approve it.

Lobbycontrol took up the matter. In May 2022, the association, which according to its statutes advocates for transparency and democracy, called on the Bundestag administration to initiate an investigation into the donation. It took more than a year before the Bundestag administration asked the CDU for a statement. One month later, in July 2023, it discontinued its investigation into the matter.

In particular, the statement stated that the offense of an influence donation had not been confirmed. It was not apparent that the party would not have made such decisions "without the donation." This means that the CDU would have campaigned for children in care homes and against rent caps and homelessness even without Gröner's money.

Record donation in court: dispute between legal experts

The lobby watchdogs persisted. After tens of thousands of people signed a petition calling for further review, they commissioned a report from party law expert Sophie Schönberger . She examined both Gröner's donation and the Bundestag administration's justification for its legality.

The renowned professor, who most recently taught at Heinrich University in Düsseldorf and will hold a chair in public law with a focus on constitutional law at the Free University of Berlin starting in September, is now representing Die PARTEI in the proceedings before the Berlin Administrative Court. The party, which has since taken up the issue, wants to compel the Bundestag administration to sanction the CDU.

On Thursday, Sophie Schönberger met with, among others, the experienced administrative law expert Stefan Lenz, who represents the "joined" CDU, as it is called in legal jargon, in the courtroom on Kirchstrasse in Moabit. Lenz has already litigated and won several cases for the CDU, for example, in the dispute over the expulsion of right-wing extremist and later AfD presidential candidate Max Otte .

Lenz moved to dismiss the lawsuit. Representatives of the Bundestag administration did the same.

Lenz focused on the alleged violation of equal opportunity between competing parties. What economic interest could the comparatively tiny PARTY have in a loss for the large CDU? Even if the CDU had to pay €2.4 million, THE PARTY would not benefit. Attorney Schönberger countered, arguing that there was an overriding "political interest" in the case.

But can Gröner actually shed light on the matter with a witness statement? Representatives of the Bundestag administration denied this. After all, all parties involved had already submitted written statements, yet the facts remained vague. "And at some point, the memory gaps appear," they said. Judge Xalter saw it differently: It was the contradictory statements that first gave rise to mistrust. Now she wants to expedite the investigation by summoning Gröner as a witness.

Regardless of the outcome of the donation proceedings before the Berlin Administrative Court, things haven't been going so well recently for the former model entrepreneur Christoph Gröner, who once set out – among other things – to end the housing shortage through mass construction. In December, public prosecutors searched the Gröner Group's premises in Leipzig and Berlin. They suspected delaying insolvency . Numerous craft businesses, especially in Saxony, could be left with their debts unpaid.

The Leipzig District Court had already opened preliminary insolvency proceedings against Gröner Group GmbH in August. At the beginning of November, the project developer's management filed for insolvency itself.

According to the Leipzig public prosecutor's office, the purpose of the searches was to find business and accounting documents, also to determine the timing of possible insolvency. There is also suspicion that employees' social security contributions had not been paid to the respective health insurance funds on time.

In Berlin, things have already gone quiet around the man who once rose to fame with plans to convert the Steglitzer Kreisel from an office tower into Berlin's tallest residential building. There has been no visible progress on the construction site, which he has since sold to the Adler Group, which is now also in trouble, for years. The Adler Group has long been looking for a buyer abroad. What will happen to this ruined investment is unclear. A similar project at the former post office savings bank on Möckernbrücke in Kreuzberg also failed.

The Steglitzer Kreisel, a scandal-ridden high-rise in southwest Berlin, has also played a role in Gröner's expressions of affection for the capital's CDU. During the 2017 federal election campaign, the entrepreneur had a giant poster for the CDU constituency candidate Thomas Heilmann placed on the facade – without charging the politician or his party for the use of the space.

Heilmann won the Steglitz-Zehlendorf constituency directly. Four years later, Gröner's €820,000 failed to carry the Berlin CDU to its goal. At the time of the donation, the CDU was ranked third in Berlin in polls, behind the SPD and the Greens. And in the 2021 election, which was notoriously flawed and chaotic, Kai Wegner only managed third place – even though the CDU had a larger budget than in previous and subsequent election campaigns. It took a repeat election two years later to bring the party, and thus also Kai Wegner, into the Red City Hall. By that time, the party said, much of the money had long since been spent.

Christoph Gröner has made himself scarce. There's a single post on his X-account. In a video from April of last year, he addresses the public with an "appeal for tolerance." He ends with the words: "The AfD is right-wing radical. You don't belong on the right; you belong in the center of society."