Deck reg requests

[Grand Inquisitor]

What abilities if any does a player have to question the composition of his opponent's deck during or after a match?

Ie, if I'm playing someone mid-event (and remember them watching my game) and they play what seems like a sideboard card G1 (eg, maindeck Ravenous Trap against my dredge deck) do I have the ability to call a judge or request a deck check?

[Grand Inquisitor]

Clarification...not that the requesting player would learn anything about the cards in the deck, just that the deck being played is accurate to its submitted decklist.

[Vennie]

Just call a judge I would say.

I once saw some1 with a reliq of progenitus maindeck get deckchecked in a legacy event (it was a trinket mage toolbox card in that deck.)

[A.-1.]

You can have a judge verify your opponent's deck for legality during a match.

[AmbivalentDuck]

I've called a judge to verify that the card was in fact maindeck. Sword of Fire and Ice maindeck in a Salvagers list vs Goblins seemed fishy.

[Clariax]

If you feel something about your opponent's deck is illegal, call a judge.  The judge can look into it.  It's pretty unlikely the judge will take the entire deck and check it, as this is pretty much impossible to do in the middle of a game.  But the judge can easily consult the decklist to see if a card in question is on it.

[LotusHead]

It is always best to call a judge if you think there might be something amiss.  They can just verify it after the match.  I had a guy request that I get deckchecked during a feature match no less. (He was shocked that I wasted his Bazaars over and over)

[Clariax]

They can just verify it after the match.

Verifying after the match won't do anything to help you, the opponent, if something is amiss.  Once the match is completed, the result isn't going to be changed.