Defensive Bidding

Defensive bidding is split into two distinct  situations - namely:

The following text is an introduction - after reading it, follow the two links above for detail.

2nd position is clear your RHO has opened the bidding
There are very few similarities in the defence mechanisms required in these positions, therefore they are being discussed separately to emphasise these differences and to avoid any risk of confusion.
In addition there are many more options available in 2nd position and relatively few in the Protective position.
Indeed despite the simpler choice of options available in the protective position, it is notable that the majority of bridge players have neglected the importance of making a correct bid in this position and simply PASS all too often!
Most of the time the opponents will be delighted by your inactivity when the results are examined!
These acute differences arise simply because of their position at the table.
I'm hoping my notes on the Protective position make things clearer and positive action is taken when it is required. This may lead to more low level competitive bidding in frequently 20-20 situations.

Now you could be in 2nd position to bid but actually 3rd or 4th position at the table! If in 3rd your partner has already passed and your LHO has not as yet spoken. Initially consider that your partner and LHO share outstanding values. Also bear in mind that you have an advantage with the opening strength hand on your right! My recommendation is to treat your required action as NO DIFFERENT than if you were in a genuine 2nd position.
If you are in 4th position the picture is radically changed:
    Your RHO could (and should) have opened light - see opening in the 3rd positionat the table

Please note that treatment in both of the above cases is very different....depending on the nature of the opening bid.

We can list here the main different situations we have to cope with.

Opponents open 1NT (12-15)

Be aware of the risks of intervention! these are just about as great as leaving a weak 1NT opening  unchallenged!
Beta uses CDH+S & Rubinsohl in 2nd position & CD+H+S in the protective position

Opponents open 1 in any suit Neither alerted or strong (16+)
Two common cases:



The attending maths is the same - presume a 20-20 situation

The last bid is in the protective position

3 Options:

See Protective bidding

Opponents open 1 Club (16+) - e.g. precision
        See TRAP
This is aggressive - as it has to be!
Opponents open 1 Diamond Precision   
Based on principle of treating artificial bids ARTIFICIALLY!
In particular we do not overcall holding a  1Major - unless making a weak 2 or 3 Jump overcall.

See BetaAcol Suggested Defence

Opponents open 1mi! (12-15 and alerted as possibly 2 or less cards)
1NT multi: lower 2 unbid suits 5-5 etc.  See 1NT overcall for complete details uses are the same as given above too. Note: Anchor suit is always lowest unbid minor and at least 4 cards.. 
2mi: (opponents). Natural 5+ card - Not both Majors
All overcalls as given for 1C without alert.
ONLY Exception is the loss of the cue-bid which is now natural as above
(There is an alternative 1NT defence, rather complex, only played by agreement - see Math6 'Attack is the best defence') Not currently in use.
Opponents open with weak 2's

T-O Double forcing. Usually shortish in opponents suit.
2-level suit bids are natural - non forcing
Rubinsohl: 2NT to 3S - all suit transfers showing a 6 card suit (transfer to opponents suit = 4/5 cards  in highest unbid major. 2NT itself requires partner to bid 3C however 2NT bidder may continue to show a fair 5+ suit and a solid guard in the opponents suit - these sequences are looking to play in the named suit OR 3NT.

Opponents open with a conventional 2-level bid

Using 2D multi as an example:

PASS and wait to know whether its weak or strong unless:
A good reason is mandatory to run the risk of interventing.

If a 2D opening peters out in 2Ma Intervene now in any good suit. A protective double may also be employed with good values but without a qualifying suit. (so more balanced in the other 3 suits)

Lucas 2's are becoming more frequently encounterd. Again only intervene with a good clear reason.

Opponents pre-empt at 3-level

For further details see our page on pre-emptive bidding
Note: Beta does not use ineffective minor pre-empts at the 3-level at all

Opponents pre-empt at 4-level
For further details see end of our page on pre-emptive bidding
usual approach is:
* of a minor showing interest in both Majors
4N over a Major pre-empt shows interest in the minors