Somewhere, someplace, there must be bidding books that discuss the principle of reliance. I’m too lazy to find those books, so I’ll just give you my own definition of this concept.

Once a partnership has located a trump fit during the auction (e.g. 1-2), it must decide whether or not to bid higher. (This is not a trick statement.) If one player keeps bidding that suit despite a weak trump holding, she is relying on her partner to have some of the missing strength.

As a simple example, say you hold:

T9852 AKJ AQT9 x

You open 1 and partner invites game with 3. What do you do? Probably bid 4. You have four top losers in spades, but you are relying on partner to have some of those missing spade honors.

What are the implications for competitive bidding? In a recent matchpoint game, my partner held:

653 AK KT32 KJ54

10 easy tricks. At the time I had a lot of sympathy for double. Partner is staring at the AK of trumps, which is a pretty powerful holding. (“Big Slick” in Texas Hold Em, which I've been playing too much lately.) After the session, however, I started thinking that double was a bad idea.

South is expecting some general values from his partner for the 1 overcall, but he isn't expecting his partner to hold anything in hearts. South has announced that his own heart suit is good enough for an independent 4 contract, which may be a serious game bid. Therefore, the AK should not be considered a trump stack, and double is a questionable call.

Double would have been much more attractive if North had overcalled 1 instead. In that scenario, South would be bidding 4 with some expectation of finding his partner with one or both top honors.

A couple weeks after suffering that -590, I found myself in an identical situation. At IMPs, I held:

AK J9 KT85 QT984

Neither side vulnerable, the auction proceeded:

Partner 1 Pass

North 1 Pass

Me 2 ?

South 4

What should I do with Big Slick in their suit? Deciding to test my little theory, I bid 5. The whole deal:

		North
		2
		KQT87
Partner		Q42		Me
93		J532		AK
A652				J9
A976		South		KJ85
K76		QJT87654		QT984
		43
		T3
		A

Regardless of the opening lead (and despite partner’s putrid 2.5 quick-trick opener), 5 is fairly makeable. We collected +400 instead of +300 in 4-X.

Hey, I’m not certain 5 was the right call, but it worked. So the next time you hold Big Slick in the opponents’ trump suit, consider the principle of reliance. If the opponents aren’t relying on each other to have the top honors, think twice before making an ‘automatic’ double.