Law 72 B3: Commentary
A player may not attempt to conceal an infraction, as by committing a second revoke, concealing a card involved in a revoke or mixing the cards prematurely.
A straightforward interpretation of L72B3 is not viable. During the play, you conceal the cards in your hand from the opponents. According to a straightforward interpretation of L72B3, when you realize you have revoked, you may not continue concealing a revoke-revealing card. I guess you are supposed to turn it face-outward so everyone can see it. Then it becomes a penalty card.
Or suppose you play the revoke-revealing card. When the trick is over, you can't turn that card over?
There is, fortunately, a very simple and common sense interpretation of L72B3. When you are allowed to conceal a card, you may conceal a revoke-revealing card; when you are allowed to mix your cards together, you may mix in the revoke-revealing card. But when you should reveal your revoke-revealing card, you may not conceal it; when you should not mix your cards together, you may not when they include a revoke-revealing card.
In other words, L72B3 upgrades any "should not" offense into a "may not" offense. (L72B3 also helps clarify a player's responsibilities.)
To rewrite this law:
A player may not deviate from any proper procedure to conceal an infraction, as by committing a second revoke, concealing a card when that card should be shown, or mixing the cards prematurely.
Following a Claim or Concession
I know of only one disagreement on the "extension" of L72B3. Suppose declarer claims. When a defender acquiesce to the claim, the defender may put my cards face down, without showing them. (This is true for any claim or concession.) With my interpretation of the laws, players do not have to show their cards even if they have a revoke-revealing card in their hand at the time.
As far as I know, that's the way most players play bridge and interpret the laws. There is nothing wrong with playing bridge this way.
But some people would rather interpret the laws to say that, following a claim or concession, a player must display his/her hand when it contains a revoke-revealing card.
The problem is, I know of no way to interpret L72B3 to accomplish that goal. Which is to say, there is no viable way of understanding that law which yields that the revoke-revealing card must be displayed after a claim or concession.