If your partner opens with a "pass," does that make you the "captain" in a bridge partnership?

Question

There are two instances: You are either third or fourth seat, and partner has passed.

In fourth seat, you are clearly the driver. After three passes, you are the one to decide whether the hand will be played or passed out.

Suppose you are in the third seat, after partner and one opponent have passed. You know that partner doesn't have an opening hand, and therefore has a hand that's no better than average. You, on the other hand, could have a passing hand, a minimum opening hand, or a powerhouse. In the first two instances, you may be worried about what fourth seat may have to say.

Does that fact give you extra liberty in bidding, knowing that your partner's choices are restricted? For instance, Larry Cohen suggests bidding strong four card majors in third and fourth seat, even though most people wouldn't do that in first or second seat.* Is it "less bad" to possibly mislead partner after s/he has passed?

*An extreme example of this is to bid "one spade" under the "rule of 15" as a semi-preemptive move.

Answer 1

You ask three or four different things here; and while Mycroft does a good job of discussing the concept, I wanted to directly answer your questions.

1. Are you the "captain"?
   No, you're not the "captain" necessarily, if you mean the person who ends up deciding where you go. Captaincy largely means one person has a well-described hand, and the other has a more wide open hand; "pass" describes a huge number of hands in first or second seat. Sometimes you do end up captain - sometimes partner does; if you open 1NT, for example, partner is nearly always now "captain".
2. Can you mislead your partner? No, you should not try to mislead your partner. You should, in every situation, make bids that are in keeping with your agreements (and convention card). Those agreements can make accommodations here though - "Could be light 3rd/4th seat", or as Cohen suggests, open 4 card majors 3rd/4th seats. Those are agreements - they're not misleading anyone, hopefully.
3. Can you take liberties? By agreement, you can do things you wouldn't do in 1st/2nd seat, and those things do include being a bit more likely to make an opening bid. Does that mean you should make bids that your partner doesn't expect or doesn't know what they mean? No, absolutely not. It just means the range of things you can do is greater - by agreement.

Third or fourth seat openings can still lead to big problems - partner could have a solid 11 count with 4 in your suit and be just short of opening 1st/2nd seat, but then they see you opening and think "Game!" when you really only have 10 yourself and 4 cards as well. Partner isn't passing permanently! I've seen people who do make inconsistent calls in 3rd or 4th seat, and it rarely works in their favor - even really quite good players capable of winning regional-level pairs events.

Answer 2

Third seat definitely can take liberties (both weak and strong). You don't have to worry about missing game, and you can preempt on hands that you never would if partner could need to judge how the hands fit for game. You can open with "a reason", and expect not to be hanged for it.

However, those liberties have to be the focus of agreements, and can include changes to system to handle them. When it goes p-p-1S-x; 2S-3H-p-4H, partner still has the key decision to make. If they expect you to be dead straight, they will double (for -790), or bid 4S (-800 into -620, or -500 into +100) if you weren't dead straight. If they expect you to take liberties, they will pass 4H on hands that really should either double to set or sacrifice, because this time you do have the hand. Worst of all is when both partners insist they are right and refuse to come to an agreement both players will stick to. Note that that agreement could be "M takes liberties a fair bit; E is pretty straight."

There are even conventions such as Reverse Drury that ask the question: "Do you actually have a hand this time, or are you playing games again?"

As far as what liberties to take, I personally believe you should have a good reason for whatever you do. So if I open 1M with a nonstandard hand (usually a 4-card suit and subminimum values), it's either because I want to preempt the opponents, or I want partner to really lead that suit (KQTx or something like that). I hope partner can figure out which one it is when it comes time for the opening lead. If I preempt with absolute nothing, I've worked out the numbers already. If I preempt with an 'opening hand', it's not the kind of hand that will hate to miss game opposite some random 11 (and would be willing to try for game opposite 4-card support and little else).

Fourth seat bidding is very interesting, because if you open, you intend to go plus. If you open with a 2 bid or a 3 bid, you still intend to go plus; so it's not a 'preempt' in the standard sense of the word. I hate passing out hands, because I never know how they're going to score. At least coming in and getting a minus means I have an idea (even if it's "likely bad"). I do it when it seems right, of course. But again, partner knows what you have when you bid.

Specifically, Pearson points (the "rule of 15" you mention) for fourth seat isn't preemptive at all - it says "the more spades you have, the more likely you will go plus, because the side with the spade fit can compete over the opponents without going up a level. The fewer spades you have, the more strength you need, because they are more likely to have the spades."

But in answer to your title; as you can see, not necessarily. A pass (playing a standard system) still contains 30% of hands, nowhere near limited enough that you're in sole control. You just have a different/wider system available to you.