Hi, this scenario just came up to me the past TN.

I'll skip all the other small detail so that we can get to the point right away. AP was playing BU control and got quite a lot of things going on in his turn. Somehow, it made him thought that the current turn is NAP's turn so he was expecting his turn coming up again. So he said “Go” and then untap his lands and draw a card right away. I ruled this infraction as GPE: HCE because there is no way NAP could have stopped AP from doing so.

Yes, there is a very small period that AP would untap his land first before drawing, but realistically, people don't really glare on opponent's board when it's coming into their turn. You're most likely going to look at your board, preparing to untap your lands, and draw from your deck instead.

I feel like even though it should have been GRV (due to that small time window), it's almost impossible for NAP to catch the mistake in any timely manner. Any thoughts?

Thank you very much.

Thanks for your detailed presentation and analysis! It seems to me that you already stated the most important aspect of the distinction between GRV and HCE in this scenario: did NAP get the chance to stop AP, or did NAP allow AP to draw the card? This is one of the classic “you had to be there” situations, but based on your description “it's almost impossible for NAP to catch the mistake in any timely manner” I will also rule HCE in 99% of the cases.

This was covered 2 weeks ago - https://apps.magicjudges.org/forum/topic/37904/

Closing this topic.

I'll point out that this situation is materially different from the one linked by Mark, in that AP created the misunderstanding and then, effectively, took two turns in a row. Dustin's analysis is sound, and - unlike the simple miscommunication in that other thread - this is an infraction. Taking an extra turn because you thought it was your turn is believable, sure - but it's also way too easy to abuse, and is entirely on the offending player; let's record that, just in case it's part of a pattern.

In the other situation, the players created the misunderstanding due to communication failure (not CPV!), so neither player is committing an infraction (follow Mark's link for elaboration on that one).

d:^D