Making or Contesting a Claim
The EBU do suggest that when it is clear that all the remaining tricks can be taken by either Declarer or the Defenders it is preferable to make a claim "rather than labouriously play out all the remaining cards". However, care needs to be exercised when making a claim - it is essential that a statement is made by the Claimant as to how the remaining cards are to be played. Just showing one's hand constitutes making a claim. If the claim is contested all play stops and the Director is called. In Rubber Bridge playing the hand out is the correct procedure, before which the defenders may show each other their hand without penalty and agree on the best defence to defeat the claim.
In Duplicate Bridge playing out the hand is not an option. The Director will first hear what statement was made by the Claimant, have all cards faced and decide upon the outcome. If no statement was made when the claim was made, the Director will rule against the claim
if it is possible for the Claimant to make a mistake. The relevent Law 70 makes it quite clear "normal play" includes making a mistake "thatwould be careless or inferior for the class of player involved". The Director will not ask the Claimant how the remaining cards are to be played as the location of a winning card may have been declared by a defender and a play to trap it concocted.
When no statment had been made at the time of the Claim, asking the Claimant how he/she intends to play the hand is not an option as a play now may be carefully constructed which will trap the winning card.
If a dispute arises that cannot be resolved, you rule against the Claim.