Louis May Greeley, What is the Test of a Regulation of Foreign or Interstate Commerce… (1887)
“ NO class of cases are more perplexing than those involving the distinction between the power of Congress to regulate foreign or interstate commerce and the so-called police power of the States. It has always been conceded that there were many kinds of laws, such as quarantine laws, health laws, etc., operating upon foreign or interstate commerce, which were within the power of the States. How are such laws to be distinguished on principle from regulations of foreign or interstate commerce within the exclusive power of Congress? ”
