[kereru67]

Which are good, which are bad, how do you rate them? What are you trying to achieve and what's the best way to do it?

[awm]

Against a strong notrump, you're usually trying to reach a making partscore; you usually won't have game unless you uncover a big major suit fit. Against a weaker notrump, it becomes more important to be able to show values, because you could easily just have game on power and you don't want them to steal the contract for 1NT undoubled when you have 25-26 high. For this reason, you often want to bid over a strong notrump on hands resembling a weak two in a major, whereas interference against a weak notrump actually needs to be more sound (since otherwise partner won't know when to bid game). Almost everyone plays a "penalty double" against a weak notrump, but this should be thought of more as a way to show values (i.e. 15+ or 16+) so that partner can judge whether to bid game, rather than actually expecting to "get them" for penalties very often.

In terms of what makes a good defence, people obviously have different preferences, but I'll give some advice below.

1. It's very important to have a way to show both majors. This is the hand type that most often yields a game (since you have TWO chances at a big major fit) and also gives the best chances of winning the partscore battle (since opponents will have to bid one level higher). Ideally you want to show both majors on 5/4 hands (not just 5/5) and this is why most people prefer 2♣ for this (giving partner the ability to advance 2♦ asking "which is the longer major") rather than 2♦ or 2♥ (either of which leaves partner on a guess with 3-3 or 2-2 in the majors).
2. You'd like to have a way to distinguish hands with one 6+ suit (the previously mentioned "weak two" type hands) where you really just want to play there, from hands with two suits (for example 5♠+5♦) where partner should sometimes select your other suit (for example with a singleton in the first suit).
3. You're probably going to have some bids that are initially ambiguous about which suit(s) are held. This tends to work better when the ambiguous bids show two-suiters rather than one-suiters, because partner can more often figure out that you have a fit somewhere when opponents bid on.

The most popular defence (by far) among expert players is multi-landy (sometimes called Woolsey in the US):

2♣ = both majors
2♦ = one major (6+)
2♥/2♠ = 5(+) in the bid suit and an additional minor suit

Double against a weak notrump would be 15+ points (not always balanced). Against a strong notrump, some people prefer to play double as 4M and a longer minor (others retain the "penalty" meaning -- which is better may depend on the frequency of psychs and/or extreme upgrades by opponents and some even go so far as to play penalty vs. 3rd seat NV notrumps and the two-suited meaning otherwise).

My preferred defence (known as "Meyerson") to strong notrump is a bit different, based on my point 3 about the ambiguous bids:

2♣ = both majors
2♦/2♥/2♠ = natural (6+)
Double = one major and one minor, 5/4 or better (either suit can be longer)

[kereru67]

Meckwell keeps the ability to play any suit at 2 level, at the cost of giving up the penalty double. Dbl is either 5-5 (5-4 at a stretch) majors or 6 card (5 at a stretch) minor. 2♣ is clubs and major. 2♦ is diamonds and a major. 2♥ and 2♠ are natural, 6 card suit (5 at at stretch). 2NT is minors (unusual NT). By "at a stretch", I mean having 3 of the top 4 honours.

[bluenikki]

♣

kereru67, on 2025-December-06, 04:04, said:

Which are good, which are bad, how do you rate them? What are you trying to achieve and what's the best way to do it?

Somewhere, Terence Reese wrote that you want to get in the auction over 1NT. But.

Unless you have a serious chance to buy the contract (6-5 with good spots, say), you should minimize the information you provide.

So I preferred a method that maybe was called "Kelsey."

2♣ = singleton or void in a red suit, at least 3 in every other suit.

2♦ = singleton or void in a black suit, at least 3 in every other suit.

2♥/♠ = natural (but I personally won't bid without shortness somewhere or 7222).

Sadly, the 2♦ bid became ACBL-illegal some time in the 90s: It had no known suit with at least 4. Of course, you could always require 4+ hearts, but that sharply reduces the frequency and raises the information.

What I now play is 2♣ for majors, 2♦ for hearts, 2♥ for spades. But that is mostly to mess with the minds of opponents who play "stolen bid double."

[DavidKok]

There are a lot of previous discussions on this topic, for example this one, or another one, or a third, or yet another.

I remember writing out my desires of a NT defence at some point - not suggesting any individual treatment, but rather some evaluation criteria for deciding between options. However, I failed to find it in a short search.

One thing that stands out to me is that people are eager to insert their pet treatment and then claim that it's good. I think that's moving too quickly, and can easily allow some poor treatments to visually get as much support as good treatments. Be careful which arguments you listen to (or, conversely, here's a carte blanche for spreading any theory you like! Most other players are, might as well join in the fun).

[mw64ahw]

It's worth learning Multi Landy with the Woolsey extension.

When I went through this process I ended up at transfer based 'Hello' which aims to put the NT opener on lead. 4th seat overalls are adjusted.
X penalty or Woolsey extension
2♣ ♦ or 5M4+m
2♦ ♥ or distributional 55xx
2♥ Majors
2♠ natural
2N some preempt
3♣ xx55
3♦ strong 55xx
3M IJO
There are also ways to show a long strong suit

The other key communication is to know what strength to expect from overcaller so that forcing bids are correctly made.

[alibodin]

I have played for many years the following simple system against weak and strong 2nd and 4th. I find often when one doubles for penalty most people have a good run out.

2♣/2♦/2♥/2♠ natural showing wish to compete.
X shows 44 or better in majors like Landy only a bid lower allows us find the better major fit.
2♣ responder has unequal by 1 majors (21 32), doubler bids their major if unequal or 2♦ when equal
2♦ responder’s majors are equal length, so doubler plays in their longer or better major
2M responder has 4 card major or one major or longer by 2 (3-1 or 2-0)

Seems to work well. 2♣ does cause confusion we often get asked is it natural? and it often scores well.

[P_Marlowe]

Hi,

The strength of the NT opening matters, if they opened a strong NT chances for game our way
are reduced, if they opened a weak NT, you may need to have the option to investigate game.

What constitutes a strong / weak NT is up to you, our definition: it is strong, if the opening
bid promises on average at least 15HCP.

If you dont want to investigate game your way, you want to stay low, if you have no fit.
If you get in, you want to take away useful bidding space, the first bid taking away space
is 2D, 2C is neutral, X gives them add. space =>
if you make the X, 2C intervention, it should enable p to take away space if it is worth.

Why exist so many? Peoble like to tinker, ..., most of the time natural is better, or at least
as good as whatever they come up with.

With kind regards
Marlowe

PS: We play Lionel, 2H / 2S are natural, which is brilliant.
X showes a 2-suiter with spades, due to this the default response by p is 2S,
taking away the space granted by X.
2C showes clubs and hearts, 2D showes diamonds and heart, which means, p can
pass those bids, i.e. the partner to the NT bidder is forced to act.

[AL78]

mw64ahw, on 2025-December-06, 08:42, said:

It's worth learning Multi Landy with the Woolsey extension.

When I went through this process I ended up at transfer based 'Hello' which aims to put the NT opener on lead. 4th seat overalls are adjusted.
X penalty or Woolsey extension
2♣ ♦ or 5M4+m
2♦ ♥ or distributional 55xx
2♥ Majors
2♠ natural
2N some preempt
3♣ xx55
3♦ strong 55xx
3M IJO
There are also ways to show a long strong suit

The other key communication is to know what strength to expect from overcaller so that forcing bids are correctly made.

I've not seen that defence before, but you have three bids to show 55xx distribution. Is it really worth having that many bids to show a hand shape which, in my experience anyway, is picked up rarely, even more so after opps have opened 1NT? I very rarely have the opportunity to bid Michaels or Unusual NT, for example. I guess it will depend on how many hands you play in a typical week.

[mw64ahw]

AL78, on 2025-December-06, 14:54, said:

I've not seen that defence before, but you have three bids to show 55xx distribution. Is it really worth having that many bids to show a hand shape which, in my experience anyway, is picked up rarely, even more so after opps have opened 1NT? I very rarely have the opportunity to bid Michaels or Unusual NT, for example. I guess it will depend on how many hands you play in a typical week.

There are a few others that play it, and I'm surprised it's not had wider recognition.

The strong 55xx bid is present in 'Hello', but the distributional one is my modification. I don't think I've ever had the strong bid, but the distributional one did result in a slam on one occasion that others weren't bidding. Most of the time we are playing opposite a weak NT. Both Majors is fairly frequent, although last week partner bid with 10hcp and a balanced 4432 finding me with xx Jx QJxx QJxxx; not a success, but in general we end up with the part score.

The transfers can also be leveraged to show other shapes, but they've never come up.

We also use some of these bids as overcalls over 1suit. 2N as some preempt often causes confusion and 3♣ as xx55 is a touch harder to defend against than 2N. Likewise for the IJOs

[pescetom]

At risk of abusing carte blanche as @Davidkok warns, I am in favour of MultiLandy over strong NT (no real experience over weak NT).

To some extent I think @awm damned the convention with faint praise, in particular playing Double as 4M5m is both standard nowadays and an essential complement of the 2M bids showing 5M4m. The biggest strength of the convention as I see it is that suits described are always either 5-4 or 6+, which gives both a greater probability of finding fit and a better protection against risk. Alternative conventions which may look similar at first sight are often at risk in terms of suit length(s) promised or clumsy in developments.

I do agree with @mw64ahw that agreements about promised strength of Interferer (and how Advancer distinguishes interest in game or not) are fundamental, whatever convention one decides.

I do not agree with P_Marlowe that natural interference is better here most of the time. There is significant room for improvement over natural, as testified by the fact that nobody (except my beginners and perhaps @mycroft) plays it Only a poor convention (or a poorly played convention) can be worse.

[jillybean]

I have played many defenses over strong nt, mostly whatever is on my partners prefer.
I prefer multi landy but only one partner plays it. It's fun experimenting with different defenses.
Natural is best unless you have have discussed insert convention name and the follow ups.

[blackshoe]

bluenikki, on 2025-December-06, 06:14, said:

Sadly, the 2♦ bid became ACBL-illegal some time in the 90s: It had no known suit with at least 4. Of course, you could always require 4+ hearts, but that sharply reduces the frequency and raises the information.

It's no longer illegal on the Open and Open+ Charts.

[AL78]

If I had the choice, I would play milti-Landy. I did attempt to play this with one partner, but the structure she had what she played with her husband was different to the structure I learnt.

For most of my bridge life, I have played one of the simpler defences i.e. Landy, Astro, Asptro, and I found that whatever was agreed, I would inevitably be dealt hands quite frequently where I wish I was playing a different one. Astro was a classic, I've lost count of the number of times I used that and it turned out to be a misfit our way.

[mike777]

Since I recently started playing multi landy, the version Gavin Wolpert plays, I noticed I tend to stay out of more no trump auctions.
I believe my results have improved.