Merkel was found to have violated the far-right party's right to equal political opportunities by criticising them during a state visit to South Africa.
Germany's highest court has backed the country's far-right party over comments made by former Chancellor Angela Merkel
Alternative for Deutschland (AfD) had complained about a statement that Merkel made during an official visit to South Africa in 2020.
The then-chancellor had said that it was "inexcusable" that Thomas Kemmerich -- a member of the pro-business FDP -- won a regional election with support from the AfD.
It came just one day after Kemmerich's surprise win in the eastern state of Thuringia and the remarks were later posted on both Merkel's and the German government’s websites.
Speaking to reporters in South Africa, Merkel had said that the outcome should "be reversed".
On Wednesday, the Federal Constitutional Court ruled that her remarks violated the far-right party's right to equal political opportunities.
The court ruled that Merkel had “negatively qualified” AfD in an official capacity and so “influenced the competition of political parties in a one-sided way".
The ruling does not have any direct consequences for the former chancellor.
The AfD had previously won a similar case in 2020 involving a former German interior minister, Horst Seehofer. Seehofer was found to have violated the party's rights by criticising its behaviour when he criticised their behaviour as "undermining the state".
Kemmerich had narrowly defeated a left-wing incumbent in Thuringia after AfD members in the state legislature voted for him instead of their own candidate.
His election was a major embarrassment for Merkel’s centre-right Christian Democratic Union (CDU), which also had backed Kemmerich.
Merkel vented her displeasure during a news conference in South Africa, saying that Kemmerich’s election “broke with a fundamental conviction for the CDU, and for me, too, that no majorities should be won with help from AfD.”
Later the same day, Kemmerich announced that he planned to step down as state governor. He led a caretaker government before his left-wing predecessor Bodo Ramelow was eventually re-elected.