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[Warhammer 40k] Can an inquisitor break the law in front of an arbitrator if they are breaking it in order to prevent/stop a heretical act?

Like the title says. Can an inquisitor commit an act that would normally result in the summary execution of anybody else by an arbitrator, if that act is done in order to prevent or stop heresy from spreading? 

Can the Lex Imperia get in the way of an inquisitor in the course of their duties?
gpt
Within the Imperium the Adeptus Arbites and the Inquisition are, in many ways, considered "equal". They are both afforded incredible leeway in how they go about their duties, and many of the laws that your general citizenry are required to follow do not necessarily apply to them. 

That being said, it is not unheard of for an Arbitrator to go after an Inquisitor if they believe that they have committed, or will commit, a heinous crime. And that's really the kicker here - the crime that this Inquisitor is committing must be, first of all, bad enough to even grab the attention of the Arbitrator, and second, be bad enough to supersede the makeshift "alliance" that they have. The relationship between the Arbites and Inquisition is surprisingly cordial and cooperative, and it is almost never in their best interest to undermine each other. 

Still, though, to answer your question specifically, an Inquisitor could skirt the law or cut corners, even in a pretty big way, and get away with it without so much as a second glance. The closer we get to outright heresy, though, the closer you will be watched. You'd better have an incredibly good explanation for doing something deemed heretical, or even borderline-heretical. If you can convince an Arbitrator that your actions ensured that heresy on an even larger scale could not come to fruition, then you'll likely be given a slap on the wrist and told to watch yourself in the future. If it becomes a pattern, and the Arbites see an Inquisitor pushing the limits on a regular basis, they'll likely get involved. One heretical act does not necessarily mean that a second will follow, but two will always become a third, and must be stopped.