This might be a repeated discussion between judges, but I want to make sure how we should do it.

In PTQ/GPT, which has top8, we sometimes do deckcheck before top8 match. Usually we just say “please submit your deck if you think you are in top8”. Player give us his deck, we check it, that's it.

Problem is, when deck has problem.

1) Deck is illegal. (Different from decklist)
It is pretty likely that, during Swiss, he played that deck which he submitted, which is illegal. In normal deckcheck, Game Loss, period. But situation is a little bit different because he didn't present this deck to opponent (he didn't actually “play” that deck).
<Question> Just saying “hey, your submitted deck is different from decklist. be careful, please fix it. ” is correct call? Otherwise, we still should issue gameloss in Game 1 of top8?

2) Marked Card, minor
In many times, their sleeves are worn and some are slightly marked. We sometimes tell them he should change sleeves before top8, which is obvious call. No problem.

3) Marked Card, major
Now, let's say we check top8 deck and realize their all lands, and only them, are slightly marked, which leads to Game Loss (or even possible DQ) in normal deckcheck, what should we do? Still same as 2)? They might have gotten advantage from marked deck during swiss, but they submitted their deck by themselves, knowing it is going to be deckchecked.
<Question> What should we do when deck is “Game Loss level marked” or even “DQ level marked”?

Originally posted by Kenji Suzuki:

This might be a repeated discussion between judges, but I want to make sure how we should do it.

In PTQ/GPT, which has top8, we sometimes do deckcheck before top8 match. Usually we just say “please submit your deck if you think you are in top8”. Player give us his deck, we check it, that's it.

Problem is, when deck has problem.

1) Deck is illegal. (Different from decklist)
It is pretty likely that, during Swiss, he played that deck which he submitted, which is illegal. In normal deckcheck, Game Loss, period. But situation is a little bit different because he didn't present this deck to opponent (he didn't actually “play” that deck).
<Question> Just saying “hey, your submitted deck is different from decklist. be careful, please fix it. ” is correct call? Otherwise, we still should issue gameloss in Game 1 of top8?

We definitely should not try to go back and issue a GL for a previous game since we don't go back to issue penalties. So it's not an issue if the Swiss deck is a problem.

As for whether a GL should be issued for the first top 8 match, I think that if players face a GL, they should be told in advance, because they haven't done anything illegal if they just present their (illegal) deck to a judge in between rounds. Telling them gives them the opportunity to verify that their deck is correct. Since we're telling them beforehand that we're potentially giving penalties, we likely won't catch any actual cheating. As a result, I prefer to treat the check as just a courtesy, to make sure that the cards are there, that the sleeves are good, that the foils aren't bent, and in general for any problems that might arise.

2) Marked Card, minor
In many times, their sleeves are worn and some are slightly marked. We sometimes tell them he should change sleeves before top8, which is obvious call. No problem.

3) Marked Card, major
Now, let's say we check top8 deck and realize their all lands, and only them, are slightly marked, which leads to Game Loss (or even possible DQ) in normal deckcheck, what should we do? Still same as 2)? They might have gotten advantage from marked deck during swiss, but they submitted their deck by themselves, knowing it is going to be deckchecked.
<Question> What should we do when deck is “Game Loss level marked” or even “DQ level marked”?

Again, I don't think we should issue a GL, because they are not at a point in the tournament where they require a legal deck, and we don't go back and retroactively issue game losses. If this is is going to lead to a potential investigation, though, they should be investigated, and of course should be DQed if appropriate.

Originally posted by Kenji Suzuki:

In PTQ/GPT, which has top8, we sometimes do deckcheck before top8 match. Usually we just say “please submit your deck if you think you are in top8”. Player give us his deck, we check it, that's it.

Problem is, when deck has problem.

If I check all decks before top 8, I will tell players of all problems that I find with those decks. At this point, deck problems are not infractions, since the players are not in a match. This is a service we provide to all remaining players in the tournament, so there is no advantage gained by any player.

This has been discussed/debated, extensively, both on the old Judge List and among the L4+ judges. As you might imagine, there are a lot of valid opinions, but here's the consensus or at least majority opinion:

If you must do courtesy deck checks, be sure the players know that they're presenting their deck to you for verification, and that D/DL Problems are penalized with a Game Loss, applied to the next game they'll play.

Note that courtesy deck checks should never result in a penalty for “failure to de-sideboard” - we verify the 75, in whatever order they're in. Ideally, the players have time to sort their decks for us - but that doesn't always happen, esp. for the last player(s) to make it in. Primarily, what I want to accomplish with these “courtesy” checks, is (a) make sure there aren't sleeve issues, (b) make sure there's no offensive altered art to show up on camera (heh), and © make sure their deck matches the list, as a courtesy to the other 7 players.

Instead of courtesy deck checks, I recommend having judges do a quick sideboard verification at the start of each Top 8 match, and mix in a few random deck checks during Top 8 - thus, providing the same service as we've provided during the Swiss rounds.

If coverage is a factor, then work with them in advance, so they can plan. If they want to cover match B, but you're going to swoop that match when the players present, coverage can adapt - cover a different match, perhaps, or line up an interview. And, it's a huge win for us if coverage mentions “there's a deck check in progress” - how many players believe they can't/won't be deck checked during Top 8?

Thanks for answer. :)
I'll try “deckchecks during top8” in my next PTQ.