Oddly enough, not the first time this has been discussed...
o How should a new mageling prepare for Wizard's War?
o Executing a Wizard's War against Masters and better..
o Wizard War
That was just a search for "+wizard +war" in the subject line - more creative use of the Search function may provide more threads.
o Case 10: When Wizards' Wars Went Wrong (not directly OT, but relevant info for your consideration)
Faeries (and Daemons and the Divine, and even Magical creatures) break the rules of Hermetic Magic regularly.
Remember - our magi often operate under different Rules than many other magics do - quite literally.
The moral and legal responsibility of mines. hmmm...
Practically speaking, I can see it going either way, depending on the mood of the Tribunal (and even more than most other cases). I would ~hope~ that the Tribunal would rule that the casting mage is responsible for an "attack" that occurred after the WW was past - hence illegal - but I wouldn't bet my life on it.
The casting is not illegal - only the later use of it would be.
If a mage casts a Scrying spell with Duration:Concentration where magi are known to walk - well, if it's gone by the time they get there, certainly no problem there.
If they cast a Scrying spell with Duration: Sun, and only use it for a moment, and then ignore it - they are not Scrying on anyone after that who walks thru that area. The fact that they could is not addressed in The Code.
Looks to me you're actually agreeing with each other, just using terms differently.
If a spell continues after the WW ends, that's irrelevant so long as the existence/effect of that spell does not break The Code.
I do not think it is too fine a distinction to point out that The Code says that a mage will not "use" magic to scry, not that they will not "have" magic that could scry. Having a crystal ball and using that crystal ball illegally are two entirely different things.
The Code is not so sophisticated as to take "intent" or "potential" into account (as written, altho' some Tribunals do in practice). The Code is broken by proven actions, not potentials or theoreticals, no matter how reasonable or historical they may be.
The spell should be removed - there is no (continued) justification for its existence - and the mage who had cast it has no justification to NOT remove it - but until told to do so, could claim it is not being used, hence no breach of the Code. (Quaesitores may feel justified in demanding verification of that claim - InMe?)
Otoh, it would be incredibly difficult to prove/disprove recent use, or to monitor such, and such a precedent might not sit well with the voters. however, I'm not sure what part of The Code they'd point to.
Parallel example - during a Wizard's War, a mage casts "Intangible Tunnel" (duration: Year) and sends a huge spell into the lab. The war ends, but the Tunnel remains. Is that an attack? Nope. Is that illegal? Not technically... but...
So I'll emphasize what I said earlier - it could go either way, largely depending on the mood of the Tribunal.