Note 379 — Chapter V · The Power of the States to Interfere with the Mails

The seriousness of this conflict was well expressed by Chief Justice Marshall in Cohens v. Virginia, 6 Wheaton 264 (1821). “To interfere with the penal laws of a state,” he said, “where they are not levelled against the legitimate powers of the Union, but have for their sole object the internal government of the country, is a very serious measure which Congress cannot be disposed to adopt lightly or inconsiderately. The motives for it must be serious and weighty. It would then be taken deliberately and the intention would be clearly and unequivocally expressed.”