I may be wrong about this, but my understanding of the CC is that if say Nevada were to enact a law saying that sales to California were subject to tariff they

I may be wrong about this, but my understanding of the CC is that if say Nevada were to enact a law saying that sales to California were subject to tariff they wouldn't be found to be in violation of the CC. Instead they'd be found in violation of some federal code that the government could enact because of the CC. I.e. the CC isn't some clause saying that free trade between states must be respected at all cost (sans the 21nd). Otherwise why would there be a federal drug law on the basis of the CC? That's a prohibition of the sale of certain goods on the back of prohibiting sales across state lines on the back of the CC. Hence the indirect reply to SeanLuke upthread. This is not a violation of the CC, but of some federal statute enacted on the basis of the CC. The distinction matters because if the CC isn't an amendment that ensures free trade the federal government could just as well use it to ensure trade restrictions between states as free trade, which it mostly does today.