The House Un-American Activities Committee was convened to flush out people who might be promoting communism in the United States. The committee began its work in 1938 as a political ploy by Republicans to discredit President Roosevelt's New Deal. Enacted to help common Americans during the Great Depression, the New Deal was seen as promoting socialism. FDR was merely trying to help out the common man and forestall the type of revolution that had, ironically, taken place in Russia and swept socialism into that country.
When World War II became the country's biggest priority, the committee was tabled. The United States would have to team up with a country whose method of government had been seen as insidious and a threat to the United States. While the committee had been mostly forgotten by the end of the war, supporters of the military complex that had been built up to fight the war were eager to find a way to keep it operational. Enter a new enemy- communism. Congressmen, eager to make a name for themselves, sought to find communism everywhere they could and one of their biggest targets was Hollywood. They found communism everywhere they looked; the holiday classic It's A Wonderful Life unfairly targeted businesses by demonizing 'old man Potter', other films depicted ragtag groups overcoming the establishment. In their minds, Hollywood was slowly trying to poison the minds of Americans into accepting communism.
So the HUAC was reconstituted and began investigating communism everywhere they looked. Oddly enough, then as now, it wasn't illegal to be a communist nor to espouse communist values. Members of the committee weren't really trying to prosecute anyone; they couldn't, as it would be unconstitutional, but that didn't stop them from grandstanding and smearing regular folks.
In fact, the notorious "Hollywood Ten" were not jailed for being communists- they were jailed for not appearing before HUAC's innuendo filled kangaroo court. Their principled stand, unfortunately, would come at a great personal cost.
