Action and Omission, Constitutional and Criminal Law

Inspired by Orin Kerr's interesting post, I've been thinking a little about the contexts in which action and inaction (or omission) matter across legal disciplines, and specifically for constitutional and criminal law.  Our good readers will know that, greatly to summarize, those who argue against the individual mandate in the PPACA Commerce Clause fight rely on the action/inaction distinction: they argue that it is permissible for Congress to regulate commercial activity, but not inactivity (and that the Necessary & Proper Clause doesn't change that conclusion).  The characterization of the mandate as regulating inaction, or economic omission, keys the constitutional challenge.

In Orin's post, he talks about Cruzan v. Missouri Dept. of Health, which involved whether there is a due process right to refuse medical treatment that would extend one's life.  Traditionally, the state has had the power to regulate suicide (see e.g., the New York Penal Law's provisions criminalizing assisting a person to commit suicide).  But Cruzan argued, in part, that because suicide is an action, it is distinguishable from refusing to take life-extending medical treatment, which is inaction.  Again, the argument depends on the action/omission distinction.  And Orin cites to a long and (per usual) incisive concurrence by Justice Scalia discussing and rejecting the action/omission distinction at least in the substantive due process context (what he will do in the Commerce Clause context is, of course, anyone's guess).

Shifting gears, people who have studied and taught criminal law know that the requirement of an action -- an actus reus -- on the part of the defendant is one of the essential building blocks of criminal law.  There can be no prosecution without an action.  More than this, the criminal law demands a "voluntary" action; involuntary actions (reflex movements, spasms, epileptic seizures, sleepwalking, etc.) cannot ground criminal liability.  The requirement of an act, however, may be subject to some degree of manipulation by "expanding the time frame."  That is, one generally can find a voluntary act if one is prepared to look beyond the context of the involuntary act causing the harm.  The epileptic seizure causing the car accident can be traced to the defendant's prior failure to take the necessary medication.  So long as the defendant's conduct "includes" a voluntary act, he can be said to have acted even though the last act (the act most proximately causing the harm) was involuntary.  It is controversial whether, given what, e.g., the language of a reckless driving statute provides, it is appropriate to expand the time frame in this manner.

But sometimes there is no need for an act at all in criminal law.  There are times when criminal law can reach omissions to act; as George Fletcher once put it, "commission by omission."  Those situations include where the defendant had a legal duty to act (e.g., a doctor); where the defendant stands in some sort of status relationship to the victim (e.g., a parent); where the defendant assumed the responsibility to rescue the victim; and where the defendant has wrongfully (though not necessarily illegally) created a risk of harm to the victim.  In the book I use to teach criminal law, there is also an old California case, Barber v. Superior Court, where the court defined the act of ceasing to provide nutrition and hydration as an omission -- the omission to continue to provide medical care.  The court in Barber then found that in the circumstances, "[a] physician has no duty to continue treatment, once it has proven to be ineffective."  That is, because the court believed that the possibility that the victim's doctors might be convicted of murder would have undesirable social consequences, it used the action/inaction distinction to neutralize that possibility.  

Here are my questions to the very good readership here.  What is the relationship of the act/omission distinction across the disciplines of constitutional and criminal law?  Given the basic doctrine above, are there modes of argument from criminal law that can be deployed in the constitutional (health care)context, or vice versa?  Could one use the time-framing strategy, or the omission strategy, somehow to get at the constitutional question?  Are there other spheres of law in which the action/omission distinction plays an important role?  And most controversially, is there anything of substance to the action/inaction (omission) distinction?  Or is it, finally, an empty shell that gives formal cover to what really lies beneath -- the hot, fraught battles of public policy and morality (I'm putting it in strong terms not to signal any strong views on my part, but only to toss a little pepper on the question)?