Something borrowed, something blue

You are a floor judge of a Standard PPTQ. During a deck check, you find that Arnold has some other cards in the deck box with the sideboard that are not on his decklist. You find 4 Jace, Vryn’s Prodigy and 4 Gideon, Ally of Zendikar in blue sleeves. Arnold is playing a Blue-White deck in green sleeves.

After investigating, you find out those are cards he lent a friend that has dropped, and you exclude Cheating. What do you do?

Judges, feel free to discuss this scenario on Judge Apps!

Answer
We expected an interesting discussion this week and we got it! Thanks for participating.

Latest IPG includes this phrase at the end of Tournament Error – Deck/Decklist Problem Definition:

Cards that are obviously not part of the deck (e.g. cards in different sleeves, tokens) are ignored when determining deck legality.

As noted by Francesco and Jon, this new phrase was meant to apply to situations where you discover a previous opponent’s card in your library, cards that aren’t legal in the format, or cards in an unplayable color. This is not what our scenario was about, so that means this situation is still a Tournament Error – Deck/Decklist Problem infraction and the penalty we must assess to Arnold is a Game Loss. We should also ask him to remove those cards from his deckbox for the rest of the tournament.

Thank you for participating on this scenario, your replies will likely help improve that wording in a future IPG version. See you in our next scenario!