A lightner double is a lead-directing double made on a slam contract, by the partner of the opening leader. It requests an unusual opening lead, which is most commonly the first suit bid by the declaring side, but not trumps or any suit bid by the defenders. This convention is NOT alertable.
When to apply Edit
A lightner double is used if all the following conditions are met:
- The defender is opposite to the opening leader;
- When the suit requested is lead, he can cash two tricks immediately, hence setting the slam. This usually implies a void in the requested suit.
Here is a good example to apply the lightner double:
- Negative double, showing exactly 4 ♠s
- Control-showing cue-bids
- 5NT trump ask
- 2 out of ♠AKQ
- South can count 13 tricks, but ...
East holds the following:
As long as a ♣ is lead, East can ruff it and set the grand slam. Therefore, he put a lightner double, asking West to make an unusual lead. In this case, it is not a ♥, not ♠, but a side suit bid by the opponents, i.e. ♣.
What to lead Edit
When a lightner double is called, the trumps or any suit bid by the defenders must not be lead. It request a lead in the following priority:
- dummy's side suit;
- declarer's side suit;
- unbid suit