From the DCI Universal Tournament Rules
34. Proxy Cards
The use of proxy cards is not permitted except under the following conditions:
 If a card becomes accidentally damaged or excessively worn through play in the current DCI-sanctioned tournament, the judge may provide a proxy replacement card at his or her discretion or require the player to sleeve all of his or her cards before play continues.
 If a card opened out of sealed product for use in a Limited tournament is misprinted, miscut, or otherwise damaged in a way that would cause the card to be marked, the judge may provide a proxy replacement card at his or her discretion.
Players are not permitted to create a proxy. When a judge creates a proxy for a player, it is included in the player’s deck. The original card is kept close at hand during the match. When the proxy is in play, replace it with the original. When the original card returns to the player’s deck/hand, swap it with the proxy. This replacement method helps ensure that the opponent is able to clearly see the intended card and to avoid confusion.
The term “proxy� includes counterfeit cards or any card that is not a genuine game card. Counterfeiters will be prosecuted to the fullest extent of the law.
I fail to see how a PSA-graded card in hard plastic could fall under either of those categories, so it would not be allowed.
