FOR A few hours on Tuesday, it appeared that there had been a breakthrough in Turkey’s dismal human rights situation. A judge unexpectedly acquitted nine people unjustly charged with attempting to violently overthrow authoritarian President Recep Tayyip Erdogan, including one of the country’s foremost civil society activists, Osman Kavala.

Alas, the jubilation among Turkey’s beleaguered liberals was short-lived. Mr. Kavala never emerged from prison; instead, he was re-arrested under a new set of trumped-up charges. On Wednesday, it became clear who was responsible for the reversal: Mr. Erdogan publicly complained that “maneuvers had been pulled” to free Mr. Kavala, and an investigation was launched into the judge who cleared him.

Who is this alleged coup plotter that Turkey’s strongman fears so much? Mr. Kavala is a cultured, 63-year-old philanthropist whose foundation, Anadolu Kultur, was known for backing initiatives such as a human rights film festival, art exhibitions and theaters. He also was one of the organizers of the Turkish branch of the Open Society Foundation, which is backed by billionaire George Soros, the subject of countless crackpot conspiracy theories among the European and U.S. far right.

Arrested in 2017, Mr. Kavala was one of tens of thousands of Turks swept up in a government crackdown following a failed 2016 coup against Mr. Erdogan. He and his co-defendants were charged with another offense: allegedly organizing mass protests in 2013 in Istanbul’s Gezi Park. There was no evidence to support this. In December, the European Court of Human Rights found there were no grounds for Mr. Kavala’s continued detention and ordered his release.

Turkey was formally bound by that decision, and Mr. Erdogan has been under pressure to release the philanthropist from senior European leaders, including German Chancellor Angela Merkel and French President Emmanuel Macron. The acquittal Tuesday at first appeared to be a concession by the regime at a moment when it is seeking Western aid for the latest crisis in neighboring Syria. Yet within hours Mr. Kavala was facing fresh charges.

The new case is even more flimsy than the first. Prosecutors claim Mr. Kavala was part of a CIA team that oversaw the 2016 attempted coup — a conspiracy they portray as led by a U.S. college professor, Henri Barkey. Mr. Barkey happened to be conducting an academic seminar on an island off the coast of Istanbul when the failed military uprising took place. The charge that he led the coup is manifestly ludicrous — and, in any case, Mr. Kavala was not present at the seminar. The charge is based on a passing encounter the two men had at an Istanbul restaurant several days later.

That one of Turkey’s leading civil society figures could be imprisoned and prosecuted on such a preposterous pretext is just one more sign of the cruelty and paranoia that has come to characterize Mr. Erdogan’s regime. We’d call on President Trump to intervene on Mr. Kavala’s behalf — except Mr. Trump is an open admirer of the Turkish ruler and has himself propagated conspiracy theories involving Mr. Soros. That means Ms. Merkel, Mr. Macron and other European leaders still committed to liberal values and the rule of law must step up.

Read more: