Thayer had previously tried anarchists accused of violent acts, and did not attempt to disguise his loathing for violent revolutionaries from abroad. In 1920, he rebuked a jury for acquitting anarchist Sergie Zuboff of violating a criminal anarchy statute. At trial, both Sacco and Vanzetti were found guilty by a jury and sentenced to death. After the trial, Thayer allegedly told a friend during the trial, "Did you see what I did with those anarchist bastards the other day?"
Thayer denied a post-trial motion for a new trial, an act for which he was condemned by various left-wing and civil liberties groups, along with some legal critics, such as Felix Frankfurter. In 1920 he rebuked a jury for acquitting anarchist Sergie Zuboff of violating a criminal anarchy statute.
Jurors in the Sacco-Vanzetti trial, however, were almost unanimous in praising Thayer for the way he conducted the trial. Reading the transcript, one sees few signs of obvious bias. What is most striking, perhaps, is Thayer's oratory, as in his charge to the jury: "Let your eyes be blinded to every ray of sympathy or prejudice, but let them ever be willing to receive the bountiful sunshine of truth...."
For their part, both Sacco and Vanzetti expressed their feelings towards Judge Thayer in unmistakable terms. In a signed article written in support of their defense committee, Vanzetti stated "I will try to see Thayer death [sic] before his pronunciation of our sentence" and asked fellow anarchists for "revenge, revenge in our names and the names of our living and dead. Both men made a pointed reference to Luigi Galleani's explicit bomb-making manual covertly titled La Salute è in voi! (Health is in You!) in response to those who had arrested, prosecuted, or convicted them.