A modern bidding system should have the same structure as a tree, with its roots deeply established and its limbs flying out to the sky. All its juices pass from the earth to the crown, with the leaves grabbing the light and passing the energy of the sun to the trunk and roots.

    In the 21st century, many bidding systems look for a symbiosis between relay bidding and a two-way exchange of information. Specific consideration must also be given to camouflage, wherever this is possible without obstructing the quality of the final contract.

    I believe strongly that a pair should use different systems, depending on the vulnerability. At white (non-vulnerable against vulnerable), I suggest a strong club-based bidding system:

1♣ opening - strong 15+ HCPs when balanced or any 17+ HCPs; 1◊ opening - 12-14 HCPs, 5+ diamonds, 4-4-4-1 shape with four diamonds and any singleton, or 4 diamonds and 5 clubs; 1♥ and 1♠ openings should be aggressive within the 9-16 HCPs range;
1 NT opening – weak 12-14 HCPs;
2♣ opening - natural 12-16 HCPs (Precision);
2◊ opening - 4+ hearts - 4+ spades, within the 4-8 HCPs range;
2♥/♠ openings - five in major and 4+ in minor, within the 4-8 HCPs range.

    Active bidding, aiming to be destructive, has been demonstrated by the world’s leading pairs to be very effective at favourable vulnerability. The Polish systems are very conservative in this respect, not to say outdated. A strong 1♣ opening allows you to bid slowly when there is a chance of a slam contract, which is one of the basic bidding postulates. It is also important for choosing the best part score. A big disadvantage of natural systems is the need to jump to show the strength. Look at this sequence:

    You waste a level of bidding in a situation when there is still a lot to discuss. There is not enough room for bidding because a whole level has been lost.

    A disadvantage of the 1♣ strong opening is the lack of resilience to destructive bidding. Favourable vulnerability practically eliminates the problem. Opponents at red do not usually expose themselves by being too active. They know that a lack of good sense may be too costly. One certainly cannot use four systems. Not only because this would be against the regulations but also because the human memory is fallible. Two bidding systems are permitted and possible to master. My suggestion is that the strong club-based system be used only when non vulnerable.