Hello fellow judges,
Despite carefully reading the IPG, I couldn't find a satisfying answer to my bewilderments about the interaction between functional reprints and Comp REL rules (TE-D/DLP).
For the purpose of this (long) post, I'll be talking about a common card : Llanowar Elves, and its functional reprints Elvish Mystic and Fyndhorn Elves, and breaking down the possible scenarii. The REL is assumed to be Competitive, cheating/attempt to gain advantage ruled out.
For each case, what would you rule, and why?

Case 1: Modern.
AP listed a 4/0 split of Elvish Mystic and Llanowar Elves.
Upon deckchecking, he's actually playing a 0/4 split of the aforementioned cards.

Case 2: Modern.
AP listed 4 Elvish Mystic.
Upon deckchecking, he's actually playing 4 Fyndhorn Elves, which is not Modern-legal.

Case 3: Modern.
AP listed 4 Fyndhorn Elves, which is not Modern-legal.
Upon deckchecking, he's actually playing 4 Llanowar Elves, which are Modern-legal.

Case 4: Legacy.
AP listed a 4/0 split of Fyndhorn Elves and Elvish Mystic.
Upon deckchecking, he's actually playing a 0/4 split of the aforementioned cards.

As far as the fix is concerned, we'll assume that AP happens to have in his binder a full playset of any of the appropriate cards.

Thanks for your answers (and patience!).

Hello, Antoine,

Let's go over the cases, and then I'll try to answer what I think is your underlying question.

Originally posted by Antoine Dubois:

Case 1: Modern.
AP listed a 4/0 split of Elvish Mystic and Llanowar Elves.
Upon deckchecking, he's actually playing a 0/4 split of the aforementioned cards.

Case 3: Modern.
AP listed 4 Fyndhorn Elves, which is not Modern-legal.
Upon deckchecking, he's actually playing 4 Llanowar Elves, which are Modern-legal.

Case 4: Legacy.
AP listed a 4/0 split of Fyndhorn Elves and Elvish Mystic.
Upon deckchecking, he's actually playing a 0/4 split of the aforementioned cards.

There are all Decklist Problems, as the decklist is either illegal (case 3), or doesn't match what they intend to play (case 1 and 4). We can reasonably assume their intent to play the 0/4 split instead of the 4/0 split because they are doing so. In all 3 cases, we'll fix the list to match the deck.

Case 2: Modern.
AP listed 4 Elvish Mystic.
Upon deckchecking, he's actually playing 4 Fyndhorn Elves, which is not Modern-legal.

I'm going to assume that they want to play 4 Elvish Mystic, so this would be a Deck Problem. Depending on when/how it was discovered, it might be either a Warning or a Game Loss. I'd be really curious as to why they were doing this, and I'd ask them.

In the really weird corner case where they want to play Fyndhorn Elves in Modern, but Elvish Mystic won't work, then it becomes a Decklist Problem. I believe that we would remove the Elves from the decklist and deck, then add Plains/Islands/Swamps/Mountains/Forests to fill it out. I'd definitely ask them why they really want to fight this battle.

This might feel weird that they're getting a Game Loss for a problem with the same card (functionally). But let's take a similar case: they write down 4 Elvish Mystic and play 4 Noble Hierarch. Or 3 Voice of Resurgence and play 3 Qasali Pridemage.

Part of having Policy clearly written this way is so that we are consistent in our rulings. We don't need to figure out how much it has affected the tournament, how much it will affect the tournament, how much better or worse it makes their deck, etc. We only need to evaluate “is the card in their deck the card that they have listed?”

The threshold for not getting a game loss is pretty low: “write down the names of what cards you are playing onto a piece of paper”. Because all of these are in Constructed tournaments, they have ample time before the event to write out a correct list. If they have questions on a foreign card, they can ask a judge, the person they borrowed cards from, or look up the card art online.

Philosophically, part of the reason that we have a Game Loss as a penalty is because this is an infraction where their opponent(s) may not be aware of its illegality. The Pridemage vs Voice question is a great example - both are playable in either the maindeck or sideboard in the same archetype. Hard-to-detect cheats are really bad, and we want to strongly discourage people from trying.

Did that help?

Just some quick comments from the ‘O’fficial perspective:

• “functional reprint” is a concept familiar to those who have played the game, but it is not a part of the game rules, nor policy;
  
• A card's Name is clearly defined in the Comp Rules (201), and is what we care about when determining deck and/or list validity.
  

d:^D

Philosophically, part of the reason that we have a Game Loss as a penalty is because this is an infraction where their opponent(s) may not be aware of its illegality.

This is a valid reason. There is another one: penalties need to act as deterrent. If not bothering with a decklist has no negative consequences, why should I spend time and energy on that?

As you only submit your decklist once, a Warning for such an infraction is meaningless: it can never be upgraded, and we cannot use it to track repeated offenses during the same event. The least sever penalty we can give that can act as a real deterrent is a Game Loss.

- Emilien