In 1932, progressive Supreme Court Justice Louis Brandeis penned one of the most famous passages in American jurisprudence. "It is one of the happy incidents of the federal system," Brandeis wrote in his dissent in New State Ice Co. v. Liebmann, "that a single courageous State may, if its citizens choose, serve as a laboratory, and try novel social and economic experiments without risk to the rest of the country."

Since then, Brandeis' famous words have been quoted or referenced countless times, appearing everywhere from legal...