Defending against 1NT (Woolsey / Jassem)
The system presented below was designed in parallel by Kit Woolsey in the USA and Krzysztof Jassem in Poland and, with slight modifications, can be used against both a strong and a weak notrump. Against the weak notrump, the 2-suited double is replaced by a penalty double.
Versus a strong NT: Bid when you feel like it, the main purpose is
to get to a part score. Still, 2-suiters are at least 5 - 4. 2-suited double applies.
Versus a weak NT: We want to find a good contract. Bid constructively. Penalty double applies.
Here are the responses to the opposing 1NT:
Double (vs strong NT): Exactly 4/ and 5+card minor
Double (vs weak NT): 15+
2: + . Partner bids 2 to ask for the longer major.
2: or . See Multi for continuation.
2/: 5+card and 4+card minor. See Muiderberg for continuation.
Further bidding after the 2-suited double:
Pass: Gotcha! (this works very well!)
2: Pass or correct
2: Bid your major
2/: To play