[PLK]

What is the rational for not allowing instant replay review of pass interference calls?

[Stone Mountain]

The rationale is that (supposedly) as opposed to other calls on the field which are supposed to be cut-and-dried, the pass interference call is more of a judgement call. They figure that if it is just a matter of opinion, better to let the call on the field stand.

[VRWCmember]

What is the rational for not allowing instant replay review of pass interference calls?

Because pass interference is a "judgment" call (which means that the officials don't really know what is and what is not pass interference); therefore, it can't be ruled by a replay official (which is, of course, pure unadulterated BS).