How does the setting affect the plot of A Lesson Before Dying?

Ernest Gaines's novel, A Lesson Before
Dying is set in Louisiana.  There,  the main character, a young black man of
diminished mental capacities named Jefferson finds himself in a liquor store after the
two men with whom he rode decide to rob it.  Unfortunately, the owner and the two men
have been killed.  So, when white men enter the store and Jefferson is standing with
bottles in his hand, he is arrested, tried, and sentenced to death by a white
jury.

The setting of Louisiana in the 1940s before
integration clearly determines the direction of the plot of Gaines's narrative.  With
the theme of the destructive powers of racism, the time and place of A Lesson
Before Dying is of much importance.  Jefferson is summarily sentenced to die
and faced with no hope of appeal.