[mlry]

As far as I remember the explosion created by a lasgun-shield effect was indistinguishable from a nuclear explosion. Nuclear weapons were banned, their use heavily sanctioned. I think there was a hint that the use of atomics would immediately bring in the combined forces of the Landsraad Great Houses totally annihilating the perpetrator. That effectively prevented the use of the lasgun-shield effect. Though the Fremen set up some shields during the final battle for Arrakeen (in the first book) to draw Sardaukar lasgun fire, thus giving them a lesson to be a little bit more restrained on the use of lasguns.

[vitiral]

IMO relying on laws for such restraint is silly. In a world of deception such as Dune, it would so trivial to plant a lasgun surreptitiously. Who's to know the cause of the resulting explosion that annihilates both gun and shield?

[tmottabr]

It is not law..

It is the fact that if the found out you would have the imperial Sardukars (that were basically invincible) plus all the Landsraad houses going after you and your house would be effectively gone. What stopped was the huge risk.

This did not stopped Paul from using it in the Arrakeen attack that we will see in the second movie. If Paul and the Freemen lost then house Atreides would be gone either way so he had more incentive to use it.

The Dune universe favor war of assassins that would happen with Landsraad approval. It is established that Atreides and Harkonnens had many war of assassins between then pre dune novel.

[vitiral]

IIRC they didn't "use" it -- i.e. they didn't intentionally shoot their own shield with their own lasgun. Rather they shielded a few underground areas and the Harkonen were using lasguns, something you're not supposed to do.

I could be misremembering though.

[tmottabr]

I think they did use it intentionally because without that nuclear explosion they could not get rid of the mountains that protected Arrakeen from sand-worms.

They invaded Arrakeen riding sand-worms that would be impossible before, it is even said in the novel that Paul was riding the biggest sand-worm ever seen that day and the Freemen considered this some kind of sign they were going to win..

now i don't remember if they shoot their own shield or they knew the Sardukar would be using lasgun and took advantage of it..

EDIT:

Ok, it seen as i am misremembering things.. They did not used a lasgun\shield combo, they used actual nukes.. Either way consequences and effects are the same..

[vitiral]

Oh I forgot about that.

I thought they were relying on a bit of a loophole: they didn't kill (m)any humans, "just" a natural barrier, which is why they could get away with it.