How did the culture of the 1950s influence Twelve Angry Men?

In "Twelve Angry Men," a jury of 12 men of various ages and backgrounds deliberates the guilt or innocence of a young man accused of crime. At trial there was an eye-witness, and it looks like an open-and-shut case. Eleven jurors, including the foreman, vote to convict on the first ballot, but one is not satisfied that guilt has been proved "beyond a reasonable doubt." That juror comes under intense pressure from the others, as their prejudices emerge and the problems they face in their personal lives are seen to influence their decisions as jurors. The dissenting juror raises one question after another about the evidence all 12 have heard and about their individual interpretations and conclusions. One-by-one, they switch, until all 12 vote to acquit the defendant.
The prejudices the men exhibit--bigotry and authoritarianism, among others--and the personal problems they face--job and family pressures, mainly--are timeless and not particularly grounded in the culture of the 1950s, but the resistance of the dissenting juror and the brutality of the criticism he withstands exemplify an era of conformity that shocks many of those who lived through it. In the decade following World War II, dissent was not tolerated. People lost their jobs and some even went to jail because of their political views. There was near unanimity among opinion-leaders of the period that harsh critics of US social institutions should be silenced. The protagonist in "Twelve Angry Men" is the rare example of a lone critic who held to principle and prevailed despite the pressure of unanimous opinion.

Twelve Angry Men deals with the racial and cultural prejudice of the United States of the 1950s. During the trial of a young man of color who's been accused of killing his own father, twelve white male jurors argue over how to settle the case. Eleven of the men assume he is guilty; one does not. Some assume the young man must be guilty due to his economic status (he lives in the slums) and his racial identity, but there is reason to doubt his guilt. One juror forces the men to reconsider the evidence.
The men makes assumptions about the accused's character based on his race and poverty, saying things like "we know what they're like" or "they're all liars." Only one juror suggests they put aside assumptions and look at the hard evidence.