It seems clear to me that if you use counterfeit nonbasic/nonland cards in an official tournament you're likely to get disqualified or even banned.
But what happens if somebody would play counterfeit basic land cards in his/her deck (assuming the weight and dimensions of the counterfeit card are equal to a official MTG card)?
On the one hand i think it would make no sense to sanction a player for doing so since basic lands have practically no monetary value. On the other hand it's probably in the interest of WOTC to only allow original cards in a tournament.
So basically my question boils down to this:
What would happen if a judge noticed a player using counterfeit basic land cards which are identical in weight and dimension to a original land card while even using sleeves in an official tournament?