Prosecutor & Spousal Rape Case

Here is a query from a colleague, and my response. Prosecutor (P) gets a horrible case of marital rape - bad facts, bad guy as defendant. P charges D with kidnaping, assault, and also rape. The hitch is that the state penal code unambiguously provides an affirmative defense to rape if the D proves the victim was his spouse. P thinks the affirmative defense statute is antiquated, sexist, etc. etc., so he charges D with rape anyway, assuming some court will throw it out. Substantive criminal law that might matter: Crimes must be defined by statute. Although defenses can be defined either by statute or judicially recognized, it's pretty clear that a defense defined by statute cannot be taken away retroactively without creating an ex post facto problem. Ethical problem? The prosecutor acted unethically. “No prosecutor should knowingly fail to disclose to the grand jury evidence which tends to negate guilt or mitigate the offense.” ABA Std. 3-3.6(b). The commentary to the Standards relates this requirement to MR 3.8(d), which deals with disclosure to the defense of similar kinds of evidence, noting that the disclosure obligation “flows from the basic duty of the prosecutor to seek justice.” Also, Std. 3-3.7 imposes a similar obligation to take such evidence into account when the prosecutor charges by information. The term “probable cause” in the context of MR 3.8(a), therefore, forbids a prosecutor to impose on the accused – and on the court – by going forward when the prosecutor admittedly knows that the case does not have any prosecutorial merit because the court will throw the case out as soon as a proper motion is made. That seems to me to be a situation that is well within the concept of frivolous conduct and, more importantly, an abuse of prosecutorial power. Also, assuming one justifies the prosecutor’s action, why should “some court throw the case out”? Wouldn’t it similarly be proper for a judge to reason that the defendant is a bad guy and that the defense is antiquated, sexist, etc. etc., and to tell the jury to disregard it in determining guilt? In short, we don’t need criminal statutes at all; as long as, somewhere, there’s a prosecutor and a judge who are satisfied that the defendant is a bad guy, just convict him and lock him up.