Trump in Dummy - Yes

It is much better to trump in the short trump hand – those trumps are not normally going to score tricks in their own right. Conversely, trumping in the long trump hand (as an end in itself) is pointless – you will make those trumps anyway. On at least 95% of hands the short trump hand will be dummy (the supporter not

the instigator of a trump suit) – so it is in dummy that you want to trump.

In (A) there is no point in trumping the two small hearts with your ♠ 65, for those trumps will (almost certainly) win by virtue of their length. Indeed reducing your trump length is positively dangerous, risking the loss of trump control. In (B) cashing ♥ A voiding dummy, then trumping ♥ 32 with ♠ 32, is extremely attractive, two extra trump tricks.

The process of trumping in dummy will normally have to be addressed right away, before drawing the opposing trumps – for drawing their trumps will use up dummy’s trumps.

Our deal revolves around the power of trumping in dummy, but has a fascinating twist (or two).

West led ♠ A v 4 ♥ and at trick two switched to ♣ Q. Declarer counted nine tricks: he’d need a ruff in dummy for his tenth. He therefore won ♣ A and led ♠ 7. East won ♠ Q and led ♣ 6, declarer winning ♣ K.

At trick five declarer led his third spade. If he could ruff it successfully in dummy he’d have his tenth trick. However the bidding told him that East would overruff.

Instead of ruffing the spade, declarer discarded dummy’s losing ♣ 5 (key play), East also discarding. Declarer could now win West’s (belated*) ♥ 4 return and ruff ♣ 9. This card East could not overruff and was declarer’s extra trick. He crossed to ♦ A, drew East’s trumps and claimed his game.

*The best defence when declarer is trying to ruff in dummy is to lead trumps. A trump switch at trick two would have beaten 4 ♥, East then winning the second spade and leading a second trump, removing dummy’s trumps.