Well, it can't be that hard to calculate, can it? According to NORML, there were 785,545 marijuana arrests in the US in 2005. Divide by 365, and we get a total of 2,155 marijuana arrests per day in the US. Now, in the US marijuana is particularly popular, and our government is abnormally harsh on marijuana, plus there are far more arrests here than any other country in the world, so we should expect the rate to be lower elsewhere. Assuming that the rest of the world makes marijuana arrests at about two-thirds the rate of the US, we get an estimate of 32,094 arrests throughout the world on a given day.