Lesh18, on 2012-February-21, 23:51, said:
If there is a convention that a 1C opening bid promises hand 13-21 points with the longest suit in clubs (majors relevant only 5+) or 3-3 in minors, is it not breaking law when I only have 11 points and make a bid 1C? Or the convention is rather a pledge that my partner sees that bid 1C with a predefined meaning and acts respectively, even though I "lied" and do not have 13 points?
No it is not breaking the law. In some rare cases, deviating from your partnership agreement may violate a local regulation, but the law doesn't restrict, on the basis of what your agreements are, what you can bid. As Edgar Kaplan famously said "an agreement with partner is not an undertaking to opponents".
Lesh18, on 2012-February-21, 23:51, said:
s it legal to say that 2C opening bid describes a strong hand 22+ points, and then my hand contains 6 clubs and 15 points and I feel like doing a "natural" bid, not the settled convention. What happens? Can I make a natural bid and say: this bid is natural? And when I do not say that, and my partner thus thinks it is a convention and acts respectively, is it illegal? I will definitely upset my partner, but will not violate the rules. Or?
This is one of those cases where local regulations may apply. In the ACBL, for example, it would be illegal to do this. If you do it, the director will probably cancel the result on the board and award an artificial adjusted score (at match points, 60% of a top to your opponents, 40% to you).
This kind of deviation is called a "psychic call" or "psych". By the laws' definition, a psych is "A deliberate and gross misstatement of honor strength and/or of suit length". Absent a regulation like the ACBL's in the case of 2
♣, psychs are perfectly legal, so long as partner is just as clueless what you're doing as opponents are. If, however, you've done it before often enough that partner begins to expect it, you have an implicit partnership understanding that the call is either A (your explicit agreement) or B (the deviation meaning). In general, when that is the case, your partner should alert and explain "it's either A or B". That's fine, but only so long as the agreement "it's either A or B" is legal in the jurisdiction in which you're playing.