Undue burden standard
One use of the standard was in Morgan v. Commonwealth of Virginia, 328 U.S. 373 (1946). In a 7-to-1 ruling, Associate Justice Stanley Forman Reed fashioned an "undue burden" test to decide the constitutionality of a Virginia law requiring separate but equal racial segregation in public transportation. "There is a recognized abstract principle, however, that may be taken as a postulate for testing whether particular state legislation in the absence of action by Congress is beyond state power. This is that the state legislation is invalid if it unduly burdens that commerce in matters where uniformity is necessary—necessary in the constitutional sense of useful in accomplishing a permitted purpose."