There isn't a double edge blade. From the 1930s into the 1950s (and sometimes longer) America was infested with an intelligentsia and a arts culture of communist stooges and fellow travelers to international communism, supporters of Lenin and then Stalinist methods of concentration labor camps and mass killings (as well as the genocide and ethnic cleansing of many peoples in the Soviet Empire). Moreover, as agents of the Soviets against the survival of their own countries none of them, on a moral level, deserved a hearing of more than 10 minutes on a hangman's gallows.
Naturally, liberals went into overtime defending this scum, whining about their innocence and unfair treatment - promoting anti-communism as the real threat to America. Fortunately the West survived long enough, in spite of these relentless termites efforts, to see the fall of European and Russian communism.
In any event, there are dozens (perhaps hundreds) that never received the punishment, let alone full punishment, so richly earned.
eace
