I'm not quoting Callan for its holding, but its discussion of what courts understood the jury trial right (which predates the Constitution) to mean. Hence the relevance of the state court cases--state courts were the ones interpreting the jury trial right before federal courts existed.
Although Callan does not find conspiracy to be a petty offense, it acknowledges that there is a class of such offenses that do not fall within the right to a jury trial, which is the only point I wanted to make. I thought it was pretty clear that I thought a speeding camera ticket was a petty offense of the sort Callan refers to.
