It is not actually a Law, as in something that you must adhere to, it's more like a rule-of-thumb that can give you guidance in certain situations.

It's also not even correct all of the time - some computer estimates say only about 50% - 70% of the time.

So with that preamble, here it is:

The total number of tricks available on a deal is equal to the total number of trump cards both sides hold in their respective best suits, where the total number of tricks is defined as the sum of the number of tricks available to each side if they could choose trumps. |

Don't leave yet - an example will make it clear what the Law

Suppose in a particular deal the opponents have an 8-card fit in ♠s while your side has an 8-card fit in ♥s.

The Total Number of Trumps held by both sides together is 16, each having an 8-card fit.

So the Total Number of Tricks that can be made must also be 16.

If your side can make 10 tricks in ♥s, they can only make 6 tricks in ♠s.

But if you can only make 8 tricks in ♥s, they can also make 8 tricks if ♠s are trump.

An important idea is that the LoTT gives you no idea of how many tricks you will be able to win if you get the contract, that depends on whether you or your opponents have the most high cards, and which side has the finesses working for them. What it does, though, is let you figure out what they can make if you know what you can make.

Think of that same example, two 8-card fits, that you have deduced from the bidding.

Suppose partner opens 1♥ and you have 3 ♥s and 13 points. Based on your bridge expertise you expect to be able to make game (10 tricks) because your side has 26 points and 8 ♥s.

So if the opponents decide to overbid your game with a 4♠ bid you can deduce that they will only make 6 tricks (because you can take 10) so they will be down 4. Down 4 doubled, of course.

Perhaps that example will give you an idea of how the LoTT can help your game.

*******

We will skip all mathematics, spread sheets, and pie-charts which might provide a "sort" of proof for the following conclusion derived from the LoTT.

*******

But here is the important conclusion:

In a competitive bidding situation it is reasonable for your side to bid to a level equal to the number of trumps held between the two of you. |

That means that if together, you and partner hold 8 ♥s, then you should be prepared to compete up to the 8-trick level by bidding as high as 2♥.

Please don't get the wrong idea here, this is not saying that if your side has 8 ♥s they will automatically be able to fulfil a 2♥ contract. We all know that would be a ridiculous statement. But it does say that if you bid to 2♥ and go down, the penalty you pay will be less than what the opponents could make in their suit.

You | Them | Pard | Them |

1♥ | 1♠ | 2♥ | 2♠ |

? |

You are wondering whether to bid 3♥.

With this hand you should not:

♠ 8 3 ♥ K Q 9 7 5 ♦ A 4 ♣ Q J 5 3

You count on partner to have 3 ♥s, so together you only have 8. You should not exceed the 8-trick level just to compete.

But change your hand to this with the same bidding:

♠ 8 3 ♥ K Q 9 7 5 2 ♦ A 4 ♣ Q J 5

You still count on partner to have 3 ♥s, so now you have 9 together. You should be willing to go to the 9-trick level.

Now look at the bidding again, this time extended a bit.

You have the first hand shown, so naturally you passed 2♠.

Now it's partner who must make a decision.

You | Them | Pard | Them |

1♥ | 1♠ | 2♥ | 2♠ |

pass | pass | ? |

Give partner this hand:

♠ 7 4 2 ♥ A J 6 3 ♦ K 2 ♣ 10 9 7 4

Partner knows you must have 5 ♥s, but since he has 4 this time he should be willing to go to the 9-trick level even though you could not.

This LoTT conclusion is one of the handiest ideas around, even if it is only absolutely correct half of the time. Because these competitive bidding wars arise again and again and again. And if you don't use the LoTT conclusion you will just have to use Gut Feeling. And if your decision turns out poorly, which excuse sounds better:

"I went with my Gut Feeling partner."

or

"Very strange, I applied the Law of Total Tricks to the problem."