Donald Trump, Xi Jinping and Jimmy Lai

President Trump understandably takes great pride in the number of unjustly imprisoned people he has helped to free from foreign dungeons. It is one of his best legacies. But one man he hasn’t been able to liberate after six years in a Hong Kong prison is 78-year-old newspaper publisher Jimmy Lai.

Mr. Trump first promised he’d get Mr. Lai out of prison during the presidential campaign in October 2024. He even said it would be “easy.” He’s kept at it since, meeting quietly with Mr. Lai’s son, Sebastien, and Mr. Lai’s lawyer at the White House. Mr. Trump also raised Mr. Lai’s case with Chinese President Xi Jinping on his May visit to Beijing. To no avail so far.

Mr. Lai remains in solitary confinement and ill health, with only 45 minutes a day for exercise outside his cell. He can draw the religious pictures he has long done to occupy his time, but he can no longer send those to family and friends. His access to books is limited.

Mr. Trump will have another chance to argue for Mr. Lai’s release when Mr. Xi comes to Washington this week for a summit. Mr. Trump is rolling out the gold carpet, with a gala state dinner on Thursday. He’s even breaking his usual pattern and is planning to meet the man he calls his “friend,” Mr. Xi, at the airport.

During his May visit, Mr. Trump’s personal appeal to Mr. Xi led to the release of Christian pastor Ezra Jin. We cheer when anyone unjustly imprisoned breathes free air again. The caveat with Pastor Jin is that his release was also China’s way of not releasing Mr. Lai.

Mr. Trump has promised he will ask for Mr. Lai’s freedom again. Mr. Xi may reply that he can’t do anything about it because Mr. Lai has been convicted under Hong Kong law. But everyone knows this isn’t true. China imposed the national-security law on Hong Kong that was used to convict Mr. Lai for communicating in innocent fashion with foreigners. One of his offenses was writing an op-ed in these pages. A word from Mr. Xi, and Mr. Lai could be on a plane the next day.

It would cost Mr. Xi nothing to free Mr. Lai, and it would prevent the international ignominy that is sure to follow if Mr. Lai dies in prison. Mr. Trump puts a premium on his personal diplomacy with foreign leaders. We’ll soon learn if Mr. Xi returns the favor to Mr. Trump for all of the Washington pomp and presidential praise.