In March 1937, Hellman joined a group of 88 U.S. public figures in signing "An Open Letter to American Liberals" that protested an effort headed by John Dewey to examine Leon Trotsky's defense against his 1936 condemnation by the Soviet Union. The letter has been viewed by some critics as a defense of Stalin's Moscow Purge Trials. It charged some of Trotsky's defenders with aiming to destabilize the Soviet Union and said the Soviet Union "should be left to protect itself against treasonable plots as it saw fit." It asked U.S. liberals and progressives to unite with the Soviet Union against the growing threat of fascism and avoid an investigation that would only fuel "the reactionary sections of the press and public" in the United States. Endorsing this view, the editors of the "New Republic" wrote that "there are more important questions than Trotsky's guilt." Those who signed the "Open Letter" called for a united front against fascism, which, in their view, required uncritical support of the Soviet Union.