In H.P. Hood & Sons Inc. v. Du Mond, the Supreme Court again rules that states may not regulate trade for the benefit of the local economy. H.P. Hood & Sons, which buys milk from New York producers to sell in Massachusetts, is denied a license to open a new New York plant under a law that allows the commissioner of agriculture and markets to refuse to license companies whose business does not serve the public good of New York. The Court rules that such preferential treatment is unconstitutional, giving unfair advantages to the local economy.