In bridge, a scissors coup is a type of declarer play that cuts communications between the defenders - hence its name. It involves conceding a loser at the right time to prevent a particular defender from gaining the lead.
The following is a simplified double-dummy illustration of a scissors coup:
Dummy
A3
4
West
2
East
2
A3
765
AJ
—
3
Declarer
A
KQ
4
T9
KQT
4
6
Hearts are trumps and West is on lead. Only two red suit losers appear to exist. However, say South wins the A and leads a heart to the king. West wins this and leads a diamond to East's ace. Now East returns a spade to effect a trump promotion. If South ruffs the spade low, West overruffs; and if South ruffs high, West's J is promoted into a winner.
Better for South to win the A and then play A and another club, discarding a diamond from hand. This loser-on-loser play would prevent East from gaining entry with the A. Whether West returns a heart or diamond, South is guaranteed two tricks with the KQT.
Example
In his book "Reese on Play", Terence Reese provides this example of a scissors coup. 1 It features a strategically timed loser rather than a loser-on-loser maneuver.
North
76
J652
West
84
East
Q4
T7632
T852
KQ74
AT983
J965
South
—
J54
AKJ93
AQ98
—
AKQT732
K
South landed in 5 doubled and received the K opening lead from West. Playing the top two spades caused the queen to drop, but the ensuing top diamond revealed the bad trump break.
South next tried ruffing a low spade in dummy, but West ruffed with the 9 and led a club to partner's A. Now East led a fourth round of spades to generate a trump promotion for the defense.
Had South led the K immediately after the A, East could give West a spade ruff but do no further damage. As the cards lie, the same effect is achieved if South discards the K at trick 1.
A3
4
2
A3