Researching the nature of sabb al-nabi (insulting the prophet mohammed) crime in Imami jurisprudence

One of Jurisprudents` debates in the book of al-hodud (determined punishments chapter), is of sabb al-nabi crime referring to insulting the prophet Mohammad (s.a). The traditions of this chapter agree to the necessity of killing its offender provided that his killer is safe from causing the loss of his life, property and decency, and a large number of jurisprudents claim the consensus on this matter. But what is doubtful, is whether this precept is be a had penalty or ta`ziri (discretionary) one. The famous jurisprudents have already discussed this precept in al-hodud chapter, and it seems that they consider it to be a had penalty. But there are some circumstances of evidence that killing of the sabb-al-nabi is not a matter of had penalty or ta`ziri one, but it is especial ruling, and it makes the famous viewpoint of being a had penalty, partly problematic.
Describing the existing evidence, this paper, on the one hand, seeks to show this claim, and on the other hand, examines the cases as the necessity of executing the percept or permissibility of it, or the need for the permission of the ruler to enforce the ordinance, or its needless of it. Obviously, given the special effects of the had penalty or ta`ziri one, there are different results which govern on this issue. This research has used a library and analytical method.