A discussion ongoing on the mtgjudge.ca facebook group:

Eternal Masters Sealed GPT, Comp REL

A player next to a match comes up to you and says that he has identified an illegal play: a player has imprinted a Chain Lightning (sorcery) to an Isochron Sceptre.

You thank the player for bringing it to your attention, and move to the adjacent table. Upon examining the board state, you confirm that a sorcery is indeed imprinted to the sceptre and you bring the imprinting to the attention of the players involved in the game.

Neither of the players claim they were aware of the mistake, and the game has moved onto turn 6 or 7, maybe even 8. The scepter entered the game on turn 2 and was used twice.

I feel this is a completely textbook case: GRV for the player who incorrectly imprinted the sorcery. FTMtGS for the opponent who allowed it to happen. Be more careful next time.

However, the overriding feeling in the thread seems to be that this is “not fair” to allow the player to keep using the scepter with an illegal spell imprinted on it, and among other potential solutions, it's been proposed unimprinting Chain Lightning, leaving it in exile, and having the player play on with a useless Scepter.

If the GRV were for illegally casting a creature (say with the wrong or insufficient mana) when multiple turns have gone by like that, the creature stays in play. I can get why watching the scepter keep casting sorceries feels somehow less “fair” but is there actually any basis for handling this differently than outlined above?

Personally i would put the sorcery, which is a card in a zone it does not belong to, back to the correct zone, probably the hand. In this case he still have something “usefull” (at least he can cast the sorcery one more time) but cant use this error for his advantage.

It definitely doesn't fit the additional remedy fix for GPE - GRV because while the start of the category sounds right the whole category is - If an object is in an incorrect zone either due to a required zone change being missed or due to being put into the wrong zone during a zone change

The zone it is in is because a player followed the instructions of a spell/ability and it doesn't meet that criteria. Expanding more, the additional remedy sections starts by saying - f the infraction falls into one of the following categories, and only into that category, perform the fix specified unless a simple backup is possible - so you have to look at the whole category not just the part that fits with what you want to do.

The choice at the time was an illegal one, but as with most GPE - GRVs that aren't noticed at the time our choice is to perform a simple backup or leave things as they are.

We need to remind both players that it was a mistake both player's made - and issuing both players with a penalty (GPE-GRV and GPE-FtMGS) reinforces that.