Source: http://www.betterbridge.com/ One standard bidding concept that often leads to confusion is the ‘reverse.’ So let’s see what this term is all about. What Is a Reverse? The most common type of reverse is a reverse by opener at the two level: OPENER’S REVERSE A non-jump bid at the two level in a new suit that is higher-ranking  than opener’s first bid suit For example,suppose opener is South:
West North East South
1
Pass 1 Pass 2
We should notice the following points about a reverse: • Opener’s first bid was one-of-a suit. • Opener’s second bid is in a suit responder bypassed — hearts. • Responder would have to bid at the three level to give preference back to opener’s first suit — 3. So responder typically recognizes a reverse because it makes the auction uncomfortable, especially when responder has a weak hand. Opener is bidding a suit for which responder is unlikely to have support — since responder bypassed it — and the auction is already at the two level.

What Does a Reverse Show?

Since responder could have as few as 6 points for a one-level response, and opener’s reverse into a suit that responder is unlikely to hold could push the auction to the three level, opener needs extra strength to make a reverse over a one-level response. Opener is expected to have at least 16 high-card points for a reverse. Opener will typically have either a medium-strength hand of about 16–18 points, or a maximum-strength hand of about 19–21 points. Since opener could have as many as 21 points, the modern style is to play that opener’s reverse is forcing for one round. So responder must bid again, giving opener an opportunity to make an invitational bid with a medium hand or get to game with a maximum hand. Since opener is bidding two suits, opener is showing an unbalanced hand. With a balanced hand, opener would either have opened in notrump, or rebid in notrump. Also, since opener bids the longest suit first, or the higher-ranking of two five-card suits, opener’s first suit will always be longer than opener’s second suit. Typically, opener has five or more cards in the first suit, and four cards in the second suit. OPENER’S REVERSE OVER A ONE-LEVEL RESPONSE • 16 or more high-card points. • 5+ cards in the first suit and four cards in the second suit. • Forcing for one round. Let’s look at some examples.
West North East South
1
Pass 1 Pass ?
 A 3  A K J 8 K Q 8 7 3   9 4 Here we have 17 high-card points and an unbalanced hand — two doubletons. We open in the long suit, 1. Partner responds 1. We now have enough strength to reverse into 2. The partnership has at least 23 combined points (17 + 6), so we don’t mind potentially getting the partnership to the three level.We have the classic distribution for this reverse: five diamonds and four hearts. K J 8  A K 10 4 A Q J 7 3   4 This hand is even stronger. We have 18 high-card points and three-card support for partner’s spades. If we count 3 dummy points for the singleton club, we have enough to take the partnership to game. However, we don’t want to jump-raise spades right away, since responder could have a weak four-card suit. A reverse into 2 is perfect. It’s forcing, so there’s no danger of stopping short of game. It gives responder a further opportunity to describe the hand. If responder rebids spades, we can be confident we have an eight-card fit.  Q J 2 K Q J 9 3   A K J 6 We have 17 highcard points in this hand, plus 1 length point for the five-card diamond suit, but it is the wrong distribution for a reverse. After opening our long suit, 1, we have to be content with a rebid of 2, a lower-ranking suit at the two level. We aren’t strong enough for a jump shift to 3, which would commit the partnership to game. The 2 rebid is not forcing, since it is not a reverse. Partner has to be aware that we could have anywhere from about 13-18 points for this sequence. Partner will only pass with a weak hand and a preference for clubs rather than diamonds.
West North East South
1
Pass 1 Pass ?
 10 4  A K 6 2 A Q 7 3   K Q 4 This hand has 18 high-card points, too strong to open 1NT, so we start with 1. When responder bids 1, we describe the hand with a jump to 2NT, not a reverse to 2. A reverse shows an unbalanced hand, not a balanced hand. What about missing an eight-card heart fit? Responder would have bid 1 with four hearts and four spades, bidding ‘up the line.’ Responder either doesn’t have four hearts, or has five or more spades and four or more hearts — in which case, responder can check back for a heart fit over our 2NT rebid.  J 6  A J 7 2 K J 9 2   Q J 4 This hand has only 13 high-card points, not nearly enough for a reverse. That’s no problem. Over partner’s 1response, we describe the hand with a rebid of 1NT.  8  K Q 7 3 A J 9 4 2   K 4 2 This is the type of hand that presents us with a rebid problem after we open 1 and partner responds 1. We don’t want to rebid 1NT with an unbalanced hand, and we must not reverse into 2 with a minimum opening bid. That would be forcing, and would get us too high when responder has a weak hand. So we must settle for a rebid of 2. Partner will expect a six-card suit, but should be aware we might have a hand like this. Alternatively, we could rebid 1NT, treating the hand as balanced, or rebid 2, treating the clubs as a four-card suit.

Reverse After 2/1 Response

The situation is somewhat different when responder bids a new suit at the two level. Now responder has 10 or more points. In fact, if the partnership is playing 2/1 Game Force, responder has 13 or more points, and we are committed to at least game. Does opener still need extra strength to reverse? In standard methods, the popular agreement is that opener’s reverse still shows extra strength, although not necessarily 16 or more high-card points. Responder’s 2/1 response has not committed the partnership to game, but when opener reverses, the partnership must have enough combined strength to go for game. When playing 2/1 Game Force, the popular agreement is that opener’s reverse at the two level does not require any extra strength, since the partnership is already committed to at least the game level. However, there are differing opinions about this, so it’s best to consult with partner.
West North East South
1
Pass 2 Pass ?
A J 7 3  A Q J 6 4 6 4   7 3 Playing standard methods, we would rebid 2 with this hand, since 2 would show extra values and be forcing to at least game. Playing 2/1 Game Force, we can rebid 2 to describe our distribution, since the partnership is committed to game.

High-Level Reverse

After a 2/1 response, opener’s bid of a new suit at the three level without a jump is often referred to as a high level reverse. In this case, opener’s second suit will be lower-ranking than the first:
West North East South
1
Pass 2 Pass 3
This auction gets the partnership to the three level before any fit has been found, so in both standard methods and 2/1 Game Force it shows either extra strength or extra distribution and is forcing to game.
West North East South
1
Pass 2 Pass ?
A K J 7 3  7 J 5 4   A K 8 6 With 16 high-card points, South has enough to bid 3 over the 2 response. With a weaker hand, South would have to choose between rebidding 2 or 2NT.

Responder’s Actions After a Reverse

When opener reverses, responder must bid again, since the reverse is forcing. With a weak hand, about 6- 7 points, reponder can: • Rebid a five-card or longer major suit at the two level. • Raise opener’s second suit to the three level with four-card support. • Return — give preference — to opener’sfirstsuit at the three level. • Bid 2NT These bids are not forcing. With a medium-strength hand, opener can now pass. With a maximum hand, opener can bid again. When responder has about 8 or more points, the partnership should have enough combined strength for game. Responder can: • Jump in a six-card or longer major suit to the three level. • Jump raise opener’s second suit with four-card support. • Jump raise opener’s first suit with three-card or longer support. • Bid 3NT. • Bid the unbid suit — fourth suit — to get further information.
West North East South
 1  Pass 1
Pass 2 Pass ?
J 7 4 2 K 6 2 Q 6 5   9 8 3 We can’t pass 2, even though we have a weak hand. Instead, we should give preference back to opener’s first suit by bidding 3. The key is to remember that opener has at least five diamonds and only four hearts. J 9 3 8 5 2 J 5  K Q 8 4 With 9 high-card points, we have enough for game after opener has shown the values to reverse. With no fit for either of opener’s suits but strength in spades and clubs, we can suggest playing game in notrump. 2NT would not be forcing. Bidding after a reverse can be a little awkward, so some partnerships prefer conventional approaches such as Ingberman and Lebensohl, but these are not standard.