What does the caption, “step on it doc” mean?

How has our understanding of the first sentence of the declaration of independence changed over time?

Population parameters are difficult to calculate due to

The 6th amendment's guarantee of a speedy and public trial is aimed at a. deterring potential criminals by fear of swift and certain punishment. b. trying those accused of crimes without undue delay and avoiding secret trials. c. eliminating overcrowded dockets in the nation's criminal courts. d. preventing jurors from being unduly influenced by public opinion.