A Lightner double is a lead-directing double of an enemy slam contract. It frequently implies a void, and asks partner for a ruff. Generally speaking, partner is asked to:
- Lead dummy's side suit, if one has been bid
- Lead declarer's side suit, if one has been bid
- Make any other unusual lead - usually partner's longest suit to get a ruff
Additionally, the double asks partner to NOT lead any suit that your side has bid.
- The Lightner double is not in effect if the opponents are sacrificing at the 6- or 7-level. In those situations, it's more practical to use regular penalty doubles.
- Playing Lightner doubles, the opening leader can also infer what to lead if his partner did NOT double. For example, if the opponents bid a side suit en route to a slam contract and partner does not double, the inference is that partner does NOT want a lead of the enemy side suit.
The Lightner double is named for its creator, American player Theodore Lightner.