Defensive bidding

Welcome to Chen-Pang He (jdh8)'s defensive bidding system! We use the distribution syntax and abbreviations provided by WBF.

This bidding system is based on Good, Better, Best by Jan Eric Larsson and my improvisation.

Over natural (1X)

(1Y)
- Dbl T/O 11+ HCP or any 17+ HCP
- 1Z 5+#, 10–17 HCP
- 1NT 15–17 HCP w/ likely stop
- 2X 5+#, 12–17 HCP
- 2Z 5+#, 4–10 HCP
- 2NT !UNT, 55+ in lowest two unbid suits, 10–15 HCP
- 3X 7+#, 5–9 HCP
- 3Y !Gambling, SOL 7+m, at most partial stop
- 3Z 7+#, 5–9 HCP
- 3NT !Gambling, SOL 7+m w/ likely stop

(1 ♣ )

2 ♣	!Landy, 4+ ♠ , 4+ ♥

2 ♦ !(R), equal preference

(1 ♦ )

2 ♦	!Michaels, 5+ ♠ , 5+ ♥

(1 ♥ )

2 ♥	!Michaels, 5+ ♠ , 5+m, 10+ HCP

(1 ♠ )

2 ♠	!Michaels, 5+ ♥ , 5+m, 10+ HCP

(1X)
- 1NT !UNT, 55+ in lowest two unbid suits

Balancing overcall

(1Y)-Pass
- Dbl T/O 9+ HCP or any 15+ HCP
- 1Z 4+#, 8–14 HCP
- 2X 5+#, 9–14 HCP
- 2Z 6+#, 8–11 HCP

(1m)
- 2m !Michaels, 5+ ♠ , 5+ ♥

(1 ♥ )
- 2 ♥ !Michaels, 5+ ♠ , 5+m, 8+ HCP

(1 ♠ )
- 2 ♠ !Michaels, 5+ ♥ , 5+m, 8+ HCP

Notrump overcalls

(1X)-Pass
- 1NT 13–15 HCP w/ stop
- 2NT 19–21 HCP w/ stop

(1X)-Pass
- 1NT !UNT, 55+ in lowest two unbid suits

After (1X)-1NT

(1X)-1NT
- 2NT NAT INV
- 3NT S/O
- 4NT QUANT INV to 6NT
- 5NT QUANT INV to 7NT

(1m)-1NT

2 ♣ !STAY, may be Garbage
2 ♦ !TRF, 5+ ♥
2 ♥ !TRF, 5+ ♠
2 ♠ !TRF, 6+om
3 ♣ !FG, 5+om, 5+M

3 ♦	!FG, 5+ ♠ , 5+ ♥

3M FG, 6+#

(1 ♥ )-1NT

2 ♣ !TRF, 5+ ♦
2 ♦ !STAY, INV+ 4= ♠
2 ♥ !TRF, 5+ ♠
2 ♠ !TRF, 6+ ♣

3 ♣	!FG, 5+ ♣ , 5+ ♠

3 ♦	!FG, 5+ ♦ , 5+ ♠

3 ♥	!FG, 5+ ♦ , 5+ ♣

3 ♠ FG, 6+ ♠

(1 ♠ )-1NT

2 ♣ !TRF, 5+ ♦
2 ♦ !TRF, 5+ ♥
2 ♥ !STAY, INV+ 4= ♥
2 ♠ !TRF, 6+ ♣

3 ♣	!FG, 5+ ♣ , 5+ ♥

3 ♦	!FG, 5+ ♦ , 5+ ♥

3 ♥ FG, 6+ ♥

3 ♠	!FG, 5+ ♦ , 5+ ♣

Over artificial forcing (1 ♣ )

Our defense was derived from Terrorist's Moscito. Note that we also use this defense even when opponents' 1 ♣ is not necessarily strong (e.g. Polish Club).

We pass strong hands since we are always given a chance to bid again. This is arguably the only sane usage of coming out after a pass.

(1 ♣ )

Dbl !TRF, 4+ ♥ , 12–16 HCP
1 ♦ !TRF, 4+ ♠ , 12–16 HCP
1 ♥ !NF, 4+ ♥ , 4+m, 5–11 HCP
1 ♠ !NF, 4+ ♠ , 4+m, 5–11 HCP

1NT	!NF, 4+ ♠ 4+ ♥ or 4+ ♦ 4+ ♣ , 5–11 HCP

2X 5+#, 5–11 HCP

(1 ♣ )-Dbl
- 1 ♦ !NF (R), 0–2 ♥ , 0–10 HCP
- 1 ♥ 3+ ♥ , 0–10 HCP
- 1 ♠ F, 4+ ♠
- 1NT !INV+ TRF, 4+ ♣
- 2 ♣ !INV+ TRF, 4+ ♦
- 2 ♦ !INV+ TRF, 4+ ♥
- 2 ♥ 4+ ♥ , 0–10 HCP
- 2NT !INV+, 5+ ♥
- 3 ♥ 5+ ♥ , 0–10 HCP

(1 ♣ )-1 ♦
- 1 ♥ !NF (R), 0–2 ♠ , 0–10 HCP
- 1 ♠ 3+ ♠ , 0–10 HCP
- 1NT !INV+ TRF, 4+ ♣
- 2 ♣ !INV+ TRF, 4+ ♦
- 2 ♦ !INV+ TRF, 5+ ♥
- 2 ♥ !INV+ TRF, 3+ ♠
- 2 ♠ 4+ ♠ , 0–10 HCP
- 2NT !INV+, 5+ ♠
- 3 ♠ 5+ ♠ , 0–10 HCP

Over strong notrump

Recommended by Good, Better, Best, we play (Meckwell) DONT against a strong notrump. We consider a natural notrump opening strong if at least half of the hands contain 15+ HCP. For instance, 14–16 is considered strong but 13–15 is not.

Over the first seat (1NT), we use the original DONT except that the other suit in 2 ♣ is always a major. Responses are natural P/C. Responder can also convert the constructive double to penalty with INV+ hands.

(1NT)

Dbl 6+X, 10–15 HCP
- 2X P/C
- 2NT FG, so unbalanced that defending 1NTx can be dangerous
2 ♣ 4+ ♣ , 4+M, 5–11 HCP
2 ♦ 4+ ♦ , 4+M, 5–11 HCP

2 ♥	4+ ♥ , 4+ ♠ , 5–11 HCP

2 ♠ 6+ ♠ , 5–11 HCP

2NT	5+ ♦ , 5+ ♣ , 5–11 HCP

We use Meckwell DONT in the other seats. Potential penalty is not that useful since at least one of us has a passed hand.

(1NT)
- Dbl 6+m or 4+ ♠ 4+ ♥
- 2 ♣ 4+ ♣ , 4+M
- 2 ♦ 4+ ♦ , 4+M
- 2 ♥ 6+ ♥
- 2 ♠ 6+ ♠
- 2NT 5+ ♦ , 5+ ♣

Over weak notrump

We play Landy against a weak notrump. We consider a natural notrump opening weak if more than half of the hands contain 14 or fewer HCP. This simple defense undermines their systems on approach over (1NT)-2 ♣ . Meanwhile, we still threat to stop in our natural 2 ♦ .

(1NT)

Dbl PEN, 14+ HCP

2 ♣	!Landy, 4+ ♠ , 4+ ♥ , 12–17 HCP

2X 5+#, 12–17 HCP

Over strong (2 ♣ )

We simply play Mathe with follow-ups same as Landy over (2 ♣ ). The strong 2 ♣ is already self-preemptive, so we don't need to worry about that.

(2 ♣ )
- Dbl !Mathe/Landy, (54)+ in majors
  - 2 ♦ !Equal preference
- 2X 5+#
- 2NT !UNT, 5+ ♦ , 5+ ♣

Over natural (2X)

(2Y)
- Dbl T/O 12+ HCP or any 18+ HCP
- 2Z 5+#, 12–17 HCP
- 2NT 16–18 HCP w/ likely stop
- 3X 5+#, 12–17 HCP, FREQ 6+#
- 3Z 6+#, 15–17 HCP
- 3NT 19–21 HCP or trick-based w/ likely stop

(2m)
- 3m !Ask for stopper
- 4m !Leaping Michaels, 5+ ♠ , 5+ ♥
- 4om !Leaping Michaels, 5+#, 5+M

(2M)
- 3M !Leaping Michaels, 5+ ♦ , 5+ ♣
- 4m !Leaping Michaels, 5+#, 5+oM
- 4M !STR T/O

Reverse Lebensohl

Though usually treated the same, there is a significant difference between (2X)-Dbl and 1NT-(2X): we cannot pass boring hands in the former situation! After a long discussion, we came to a conclusion that reverse Lebensohl with Rubens advances is a better alternative than transfer or standard counterparts.

As opposed to the standard/original Lebensohl, this 2NT relay handles constructive hands (8+ HCP or 7+ HCP by passed hand) while directly bidding a suit below 3X is weak. Since an in-shape takeout is short in the adverse suit, advancer is more likely to have a stopper. Inviting with 2NT right-sides the contract more often than not.

(2 ♣ )-Dbl
- 2X COMP, 4+#
- 2NT !INV+ (R)
  - 3 ♣ !NF MIN (R)
  - 3X FG, 4+#
  - 3NT MAX BAL
- 3 ♣ !TRF INV+, 4+ ♦
- 3 ♦ !TRF INV+, 4+ ♥
- 3 ♥ !TRF INV+, 4+ ♠
- 3 ♠ !Ask for stopper

(2 ♦ )-Dbl
- 2M COMP, 4+#
- 2NT !INV+ (R)
  - 3 ♣ !NF MIN (R)
  - 3 ♦ !FG, 4+ ♣
  - 3M FG, 4+#
  - 3NT MAX BAL
- 3 ♣ !STAY
- 3 ♦ !TRF INV+, 4+ ♥
- 3 ♥ !TRF INV+, 4+ ♠
- 3 ♠ !Ask for stopper

(2 ♥ )-Dbl
- 2 ♠ COMP, 4+ ♠
- 2NT !INV+ (R)
  - 3 ♣ !NF MIN (R)
  - 3 ♦ FG, 4+ ♦
  - 3 ♥ !FG, 4+ ♣
  - 3 ♠ FG, 4+ ♠
  - 3NT MAX BAL
- 3 ♣ COMP, 4+ ♣
- 3 ♦ COMP, 4+ ♦
- 3 ♥ !TRF INV+, 4+ ♠
- 3 ♠ INV, 5+ ♠

(2 ♠ )-Dbl

2NT

!INV+ (R)

3 ♣ !NF MIN (R)
3 ♦ !FG, 3= ♥
3 ♥ FG, 4+ ♥

3 ♠	!FG, 0–2 ♥

3NT MAX BAL

3X COMP, 4+#
3 ♠ !Ask for stopper
4 ♣ F, 5+ ♣
4 ♦ F, 5+ ♦

Note that this structure also works for artificial (2m) openings without further modification.

Defensive bidding system