This is a theme that often surfaces in bridge discussion. I thought it would be useful to list the factors that would influence me to open 1NT or 1M, once and for all. At least this will allow me to simply point interested parties to this article! 

Why would anyone want to open 1NT when 1M neatly describes the main feature of the hand, the 5-card major suit, which is also a very live strain possibility? In a standard system (featuring 15-17 NT openings and a forcing NT response to the 1M opening), the main reason is that you will have a difficult time describing your high-card power if you open 1M. After 1M-1NT, new suits can be as weak as 12 HCP, and the 1M-1NT-2NT shows 18-19. Rebidding your majors with 5332 is a big no-no (partner will be misled as to both your strength and your suit length, expecting 6 cards there, if you do this!). The solution is to temporize with the cheapest natural new-suit bid. It is a bad kind of solution; no one feels comfortable rebidding Two Clubs in this auction with KJ1042 AQ5 K10 Q72. But it is your best bet if you decided to open One Spade and heard One Notrump in response.

On the other hand (bridge always has another hand), if partner does not reply to your 1M opening bid with 1NT, you are probably fine. If he raises you, you are certainly ahead of the NT openers (this is the worst case scenario for them). If he bids something else at the 2-level, you can rebid 2NT without misleading partner as to your strength.

This is not an easy situation, and if there were a perfect solution, it would be already widespread. Always opening 1NT will miss many desirable 5-3 fits. Never opening 1NT will lead to awkward auctions and missed games with the points divided 15-9 and the like. The best answer lies somewhere in the middle, but how to identify that middle? This is what this article is for.

We are assuming here that the question is whether to open 1NT with a 5332 hand containing a 5-card major, by the way. Devotees of the 1NT opening will do it with 5422 or even stranger distributions, but here we are not that creative (these hands will often have a comfortable rebid, eliminating the main issue with the 1M option). 

So, here we go, with a list of questions which you should ask before deciding. Remember, none of this criteria should be taken in isolation. If a hand fails a minor criterion but is overall fine for opening 1NT, do it.

1. Does the hand look notrumpy? That sounds vague but it is very important. A notrumpy hand has good intermediates, a preponderance of queens, a bad suit. Compare AK1098 AKJ 852 93 with J9852 KQ9 AJ KQ8. Your gut feeling should tell you which one is more suited to a 1NT opening. The borderline cases (AQ109x KQ10 J2 A103) will give you more trouble. Note how this second hand has a weak doubleton and a good suit, but it also has nice intermediates (that 10 of clubs can easily become a second stopper; but perhaps not. A109 would be better). When you get a borderline case, move to the next question.
2. Where is your doubleton? The ideal NT distribution has a doubleton in clubs. (Why do they always pick on clubs?). If the doubleton is in clubs, opening 1M means having to rebid 2D over a 1-level response, and 2D is always less suspect than 2C. Rebidding 2D with 3 cards exposes you far too frequently to an unwanted raise. The worst doubleton to have in a 1NT is in the other major, because this will often lead to a transfer from partner and perhaps a 5-2 fit when a 5-3 fit is available.  
3. What is your major?  Not all majors are created equal. Opening 1NT when you have hearts has a very clear advantage of preempting a 1S overcall. Opening 1NT with spades has less of an upside. 
4. What is your position at the table? 1st and 2nd position should skip over this question, but if you are in 3rd position, you should have more leanings towards opening 1NT. It is more preemptive by itself, and interference over a NT opening is much less precise than over a 1M opening. So, you are giving a tougher problem to the 4th bidder if he has a nice hand. Conversely, if you are in 4th position, lean towards opening 1M, especially with minimum hands, in which game requires a maximum from partner. After three passes, partscore bidding becomes more valuable.
   
5. Are you playing matchpoints or imps? Matchpoints places a higher premium in competitive auctions and in finding the best strain at all times, whether you have a game or not. Imp strategy involves bidding tight games and divulging less information in the process (to maximize lead and defensive errors). So, in borderline cases, 1M is to be preferred at matchpoints, 1NT at imps. 
6. Are you vulnerable? At imps, if you are vulnerable, the main goal is to get to a game if it is in any shape or form within reason. So, run for daylight and open 1NT in those borderline cases. In matchpoints this is a less pressing issue, so consider the other factors. 

This is a theme that is not well explored in the literature, or on the web. A recent discussion within our social media groups has prompted me to write down some principles that will help your partnership to deal with this rather common situation. 

Vulnerability is an important consideration in almost all competitive decisions, but this particular case is one in which its role is even more crucial. Some facts must be kept in mind by all players when they are deciding how to react after 1NT is doubled for penalties:

Scoring overtricks
Vulnerable overtricks are worth 200. Nonvulnerable, they are worth only 100. This means that the scale of rewards in your doubled 1NT contract can be either 180, 280, 380... (if nonvulnerable) or 180, 380, 580 (if vulnerable). 

Scoring undertricks
People are more familiar with the scale of rewards for defeating a doubled contract, but for completeness' sake, they can be either 100, 300, 500, 800, 1100... (nonvulnerable) or 200, 500, 800, 1100... (vulnerable). The two sequences are identical after 500 (identical if you keep in mind that a nonvulnerable player must go down one more trick to pay the same penalty as the vulnerable player).

When you want to escape from 1NT doubled, these numbers must be very clear in your mind. You have to judge which is the pathway that gives you the highest (or, the least worst) expected value. 

Some defenses against a penalty double "turn the cube" and force the partnership to play 1NT redoubled . These scales become even more important in that case, because 1NT redoubled is game.  The possible values are:

For making your contract:
560, 760, 960... (nonvulnerable)
760, 1160, 1560... (vulnerable)

For going down:
200, 600, 1000, 1600... (nonvulnerable)
​400, 1000, 1600... (vulnerable)

Keeping the above numbers in mind, there are some systemic considerations to be discussed now. The decision of sticking it out or running is heavily influenced by your agreements. If you cannot describe your hand appropriately, the situation becomes more problematic. 

For example, suppose your partner's weak notrump opening is doubled and your escape methods are the very very simple "system on", meaning, 2 Clubs is Stayman, 2 of a red suit are transfers, 2 Spades are clubs, 2NT shows diamonds.  (Although I am not endorsing this method, it has the very clear advantage of simplicity and of often placing the contract in your partner's hand, which is usually desirable. Doubler has the majority of power and partner must have some honors to be protected from the lead). The only "extra" is the redouble, which you use to escape to 2 of a minor (partner bids 2 Clubs and you correct to diamonds if you have long diamonds).

This scheme is ok for all hands with 5-card suits. It has some trouble in the weak 4432 and 4441 hands without both majors. (With both majors you bid 2 Clubs immediately). Imagine that you have a weak hand and 4 hearts and 4 diamonds, 2 spades and 3 clubs (i.e. a 2=4=4=3 hand). You will have to stick it out in 1NTx, or guess a red suit. 

(By the way, especially if you are playing a weak notrump, guessing a red suit is not as bad as it seems. The opponents often have a game in this situation. And if you guess wrongly they sometimes don't have the right hand to double you there. That said, it is clearly better if you can ask partner's opinion about the reds).

The scheme of responses you chose basically forces you to (either guess or) stick it out in 1NTx with balanced hands. You have a minor escape hatch with 44 in the majors (you can stretch it with 43 there), but otherwise you will be committed to playing 1NTx with those hands. Not so bad with the right vulnerability, but worrisome if you are vulnerable. 

In any case there are some clear principles emerging: don't be afraid of playing 1NTx if you have a balanced hand (sometimes this is your safest harbor in the storm. Sometimes there is no safe harbor in the storm). Take it out if you have a 5-card suit and a weak hand (the expectation of 2.5 cards with partner, which is probably close to the mark, shows that this is a reasonable trump suit -- and the weaker you are, the more important it is to get away from notrump when you actually have a reasonable trump suit).

The next post will look at this situation from the other side: your partner doubled their 1NT opening. 

Our friend from Argentina, Ernesto Muzzio, gave us another tough scenario in the bidding:

This article is the first of a series in which I will discuss some bidding notions that appear weird, and perhaps even mistaken, to my eyes.

We have plenty of interesting hands from the trials to publish, but we will interrupt that series to give a bidding judgment problem, offered by the great Argentinian player Ernesto Muzzio.

If it is not clear by the diagram, no one is vulnerable. 

Some of our experts' opinions follow:

Diego Brenner: DBL, meaning "I will be happy if you bid". It's very comfortable to Pass, but in my opinion the comfort zone is a dangerous one in Bridge.

Marcelo Branco: Pass. I don't see any particular reason to act here, since I have a pretty normal opening bid.

Paulo Brum: Pass. Without any special agreements, since my pass is not forcing, the double is commonly interpreted as an expectation to defeat 4 Spades, and as a positive opinion that the 5-level is too dangerous for us. I don't have any assurance of either of those opinions, so I pass. My pass will very often reveal a shortness in spades, allowing partner to reopen if it seems profitable.

Nowadays, many partnerships are playing this Double as Diego described it. There are pros and cons, as in any bridge convention, but in general I (Paulo Brum) like it, particularly in IMP scoring. It helps us bid with more assurance, more often, at the cost of having some 590's and 790's scored against us here and there. Pushing the opponents out of their chosen contract -- either to 5m doubled or to 5S -- will often result in much bigger profits. 

We want to hear about your opinion in the comments!