Playing IMPS in the local team game, you hold the following hand NV vs Vul. 8 AKJ86 A AKJT63. Partner opens 1D in first seat, and after a Pass on your right, you bid 2C, GF. This now goes 2S on your left, Pass by partner, 3S on your right. What now?
First, it would be nice if those pesky opps would stay out of your auctions and let them stay uncomplicated. And second, there are a lot of points in this deck, or distribution. You are aware that partner and the person on your left like to bid, but the person on your right is pretty reliable. So does that say anything about the hand. Partner is unlikely to have psyched in first seat, that is not his style, so you can rule that out to start, and the person on your left is frisky, but not crazy, so EW should have a lot of Spades and shortness somewhere. Question is, how does that help you.
The person at the table now bid 4S with this hand, trying to show the hand strength, but I think that gets you to high early. I actually like a Pass with this hand, to see what partner does. I think that will leave you much better prepared to bid something reasonable. Over the 4S bid, partner bid the expected 5D, and over 5H, now bid 5N, which is a something bid. At this point, this hand guessed, and bid 6C, which bought the contract. The opening lead was the K of Spades and dummy tracked with AJT 953 KQJ864 8, not the dummy of your dreams. Since this person was unsure of what 5H meant, they did not correct 6C to 6H. Although I feel a bid of 6D might be warranted, since this hand is going to be useless in Clubs for the most part.
At the table, it looks like you are now prevented from setting up the Diamonds for any Heart pitches, but you have to try and make it. You can win the A of Spades, and decide what rounded suit hook to take, but the Hearts only need to be 3-2 with the Q on side to avoid a loser there. The Clubs need to be 3-3 or 4-2 with a tripleton or doubleton Q on side to avoid that loser. So it appears the Heart hook is the winner, and it actually works on this hand. Add that to a 4-2 Club break with no ruffs coming, and 6 Clubs can come home with the Heart hook. In the interests of safety, I will not reveal the line taken at the table, except to say that it did not make.
Back to the bidding, the reason I like a Pass over 3S is that partner is going to do 1 of Double, bid 3N, or bid 4D. Either of the first 2 are things you like, since you can bid 4H or 5H (my preference) over them to show a massive 2 suiter, on the Pass and Pull is stronger theory. And over 4D, if you bid 5H and partner bids 6D, you are fairly happy to pass with the A of Diamonds and all of the tricks in your hand. The direct bid of 4H over 3S does not begin to do your hand justice in my opinion.
The question asked at the table was if the Pass had to be forcing. If you are playing 2/1, it does, since you are below game, you are in an absolutely forcing auction.