Lesson 3: Intervener’s Role (Overcaller/Doubler)

Make an overcall or takeout double whenever possible. Competing will prevent the opponents from having a free run during the auction.
There are three reasons for an overcall. (1) Lead -directing. (2) Push the opponents too high, or stop them finding their best spot. (3) You might make your own contract.
An overcall (8 – approx 17 points, and a good five+ card suit) might have the strength of an opening bid, but it’s not called an “opening bid” because an opponent has already opened. ♠AQ875 ♥842 ♦82 ♣KQ4 The player on your right opens 1♦ , so you would overcall 1♠.  You need a good suit, five+ cards, and two of the top three, or three of the top five honours (AKQJ10). Even with one fewer club honour, an overcall would be recommended here. Partner raises your suit, just as if you had opened.

♠J943 ♥5 ♦K5 ♣AKQ954 If your suit is lower ranked than opener’s (here your right hand opponent opens 1♥), an opening hand is necessary if you decide to overcall. You’re contracting for an extra trick, and you don’t know partner’s, or the next opponent's, strength. You need a good club suit, like this, ♣AKQ954 , to overcall with 2♣, and you need opening values too. 

A jump overcall, (bidding one or more levels higher than necessary), shows a weak hand with a long suit, like a preemptive opening. All the honour cards need to be in your long suit.
You often muddy the waters for the opponents, who may have a lot of points and be trying to find a fit. You’re not expecting to make your contract, but rather, hoping the penalty for going minus is not as big as what the opponents could have made. Because you might be doubled for penalty, you need around six playing tricks to bid this way. e.g. ♠7 ♥KQJT853 ♦75 ♣732 The opponents open 1♦, and you should make a jump bid to 3♥, showing a long suit with few points. This hand, with the seven card suit ♥KQJ10853, missing only the ♥A is worth 6 playing tricks all by itself.
The more cards in your long suit, the higher you should jump.

Partner doesn’t have to bid, but they should raise your suit if they hold a few trumps. There’s not much point in bidding their own suit when you’ve told them there’s only one place to play. ♠854 ♥9742 ♦A943 ♣86 If partner overcalled by jumping to 3♥, you might as well raise to 4♥, because you hold four trumps.   Hands with big fits and few points are “offensive” hands will do well only if their suit is trumps."Defensive" hands are ones where you hold honour cards in other suits, fewer trumps, and and are likely to take tricks in defence.

Take out Doubles
A double is a really flexible bid. It takes no room in the bidding, but suggests your side could be in the auction. The person who doubles includes their partner in the decision–making process. If you don’t have a long suit, maybe partner will be able to help. 
Double was originally used to increase the penalty when opponents bid too much, but it’s unlikely to work that way at low levels. So, most doubles are now known as takeout doublesbecause they ask partner to bid, and show an opening hand (13+), shortage in the suit opened, and the ability to support the other three suits. Count shortages when deciding whether to double, but remember they won’t improve the hands if you end up in no trumps. So be happy about your shortage, but be a little careful too.
Let’s have a look at this hand: ♠KQ75 ♥AJT2 ♦5 ♣K974
You have a good hand, but you’re not sure where to play it. You can’t overcall, as you don’t have a good five-card suit, and anyway who knows which suit would be your best spot? That will depend on partner’s hand.
So, say “Double” and that will kill three birds with one stone!

♠76 ♥AK74 ♦A642 ♣A94. When West opens 1♠, North has a good hand with shortage and would like to play in any suit except spades, so North doubles. South responds 2♦ their longest suit. It’s essential to answer partner when they double if the next person passes, (even if you have nothing), because if you pass, the contract will become 1♠ X and that will give you a bad result if it makes even seven tricks, as the score will be more than doubled. South will make eight tricks in diamonds, losing two spades, one heart, one diamond and one club.

It’s less important to have a shortage in opener’s suit when you hold more points. If you have a good suit, but think it’s too strong to overcall, (17+ points), you’re better to start with “Double”, and then show your suit over partner’s response. This way the hand won’t be passed out (as an overcall is not forcing).

Competing Against 1NT
Giving the opponents a comfortable auction after an opening bid of 1NT doesn’t usually lead to a good result. Although competing has its risks, the occasional poor result is outweighed by the good results from taking the opponents out of their comfort zone. It’s dangerous to enter the auction with just a five-card suit. If partner doesn’t have a fit, the opponents may be able to double for penalty. A six-card or longer suit, or a two-suited hand is safer. The better the suit, the less likely that the opponents will double for penalty. With two suits, the odds improve that partner will have a fit for one of them. There are many agreements over 1NT, such as Landy, Cappelletti and DONT. Most focus on one-suited and two-suited hands. 

Two-Suited Overcalls
Most modern partnerships have agreements on how to enter the auction with two-suited hands – two five-card or longer suits. If partner has a fit with both suits, the partnership may even make game on very few high cards.
The Unusual notrump convention is: A jump to 2NT over the opponent’s opening bid of one-of-a-suit shows at least five cards in each of the two lower-ranking unbid suits. (e.g. 1♥ 2NT = 5+ cards in both minors)

Michael’s Cuebid
A direct cue bid of opener’s minor shows at least five cards in both majors (e.g. 1♣ 2♣ = 5+ cards in both majors)
A direct cue bid of opener’s major shows at least five cards in the other major and a minor. (e.g. 1♠ 2♠ = five+ hearts, and five+ in a minor).