Halevy was the sole judge in what became known as the "Kastner trial," a libel lawsuit against Malchiel Gruenwald, a hotelier, who accused Rudolf Kastner of having been a Nazi collaborator.
Shlomo Aronson in his book Hitler, the Allies, and the Jews, claims that Gruenwald's personal file, released by Israeli Home Intelligence, provides a very different picture of Gruenwald's early activities.