More on the Proposed Act/Omission Distinction — And What Does It Mean To “Mandate” an Act?

I appreciate Jonathan Adler’s response on the nature of Randy Barnett’s proposed act/omission distinction on the scope of federal power. Given that this is a proposed distinction, not one presently recognized in the caselaw, my real interest at this stage is just getting a sense of how such a distinction is supposed to work — not, as Jonathan has focused on, the degree to which the general category of distinction would be “precedented” or “unprecedented.”

In particular, I’m just trying to understand if the proposed test is that Congress can regulate it so long as there is some affirmative act included in the prohibition, or rather if the proposed test is some kind of more complicated test that either includes some nexus requirement between the act or omission or else has some other requirement beyond an act. In the comment thread, Jonathan says that he assumes there is some sort of nexus requirement. But I don’t know if that is what Randy has in mind.

While we’re on the topic, I’d also be interested to know more on the meaning of “mandate” in the proposed distinction between regulating acts and regulating omissions by “mandating” conduct. What exactly does it mean to “mandate” action? For example, does the government “mandate” an act if a person has the choice of paying a fine instead of acting? What if the fine is very low, like, say, $400? $100? $1? Does it depend on the mechanism for collecting the fine? It seems to me that the difficulty is that the law often encourages people to take a certain act through economic incentives. For example, Congress might pass a tax break for people who do something that Congress wants people to do. Where exactly is the line between a (presumably) permitted incentive to act and an illegitimate mandating of conduct?