ACBL, from the NABC
Matchpoints
I'm just presenting the auction without the actual hands since I'm primarily interested in a LA discussion.
N opened 2D, Flannery. E bit 2NT; he believed that this was Unusual showing the minors. No alert from W. S passed and W bid 3NT after an extended (1+ minute) hesitation. After S doubled in the passout seat E ran to 4C.
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Prior to the opening lead W was asked if they had an agreement about 2NT; she admitted being unsure as to its meaning.
The hand was played out and the TD summoned. The NS position: E has UI from W's hesitation that W may be unsure of the meaning of 2NT. This demonstrably suggests not playing 3NTx. Passing 3NT is a LA. Score should be adjusted to 3NTx making however many tricks it makes.
The TD ruled that passing 3NTx was not a LA. NS disagreed; I'll post the hand later and you can make up your own mind. I'm interested in opinions on whether the hesitation demonstrably suggested running (to a player who was happy to sit for 3NT undoubled), and whether S's double has any whiff of a 'double shot' not worthy of protection.