In certain defense strategies the partnership attempts to communicate information about certain suit lengths, attitude, and also preference. Another element is added by the obvious shift principle, which, in most of the occurring situations, is a discouraging signal to partner's lead showing two things. First, the partner does not like partner's suit, and secondly, if the partner so desires, the player can stand for him to make the obvious shift - the side suit that appears to be best for the best line of attack.

Foundation of the Concept

The concept behind the obvious shift principle is that the partnership does not have to change any of the elements of the agreed signaling method. The partnership merely has to add it to the partnership agreement already in place. The idea behind the concept is indeed only an expanded attitude signaling system designed solely to permit one partner to inform the other partner either on the opening lead and at certain other times during the defense period whether a shift should be executed.

Note: Pamela Granovetter and Mr. Matthew Granovetter published the book titled A Switch In Time: How To Take All Your Tricks On Defense.The book was published by Granovetter Books in the year 1994. ISBN-10: 0940257173 / ISBN-13: 978-0940257177.

When is the Obvious Shift Principle Applied

At Trick 1, partner of opening leader compares the led suit and obvious shift suit. Encouragement, upside-down or standard, denies tolerance for the obvious shift suit. Discouragement actively confirms tolerance for the obvious shift suit. This applies whether opening leader will maintain the lead or not.

Rules for Identifying the Obvious Shift suit, in order of priority:

Negatives

1.	The Obvious Shift cannot be the suit led.
2.	The Obvious Shift is never trumps.
3.	The Obvious Shift is never a suit headed by the A-K-Q or four of the top five honors.
4.	The Obvious Shift in a suit contract is never dummy's singleton or void.
5.	The Obvious Shift is never a natural suit bid by declarer.

Positives

The opening leader's bid suit is the Obvious Shift:

1.	If the opening leader has not bid a suit, the leader's partner's bid suit is the Obvious Shift.
2.	If both defenders have bid suits and the opening leader starts with an unbid suit, look at the suits and choose one of them by applying the rules below.
3.	When the defense has bid two suits or when the defense has not bid any suits:
	a.	against a suit contract, a three-card suit headed by at most one honor, Ace, King, Queen, Jack, Ten, is the Obvious Shift.
	b.	against No Trump, dummy's shortest suit is the Obvious Shift, even a strong holding such as Ace-King doubleton.
	c.	when there is no weak three-card suit, the shortest suit is the Obvious Shift. But against a suit contract, this cannot be a singleton or void.
	d.	when there are two equal length suits, either of which might be the Obvious Shift, look at the number of honors. The suit with fewer honors is the Obvious Shift. If the suits have an equal number of honors, the lower-ranking suit is arbitrarily deemed to be the Obvious Shift.

Implementation Details

Requirements for Encouragement in Obvious Shift suit if suit is:

1.	Jxx or weaker:	the Ace or King, or Queen vs. No Trump
2.	Qxx:	the Ace or King
3.	Kxx:	the Ace or Queen
4.	Axx:	the King or Queen

To Call for an Unusual Switch

Play an unusual honor card. However, opposite a lead from the top of an honor sequence, when dummy does not have a singleton, vs. a trump suit, an unusual honor shows the top of the next lowest sequence, to allow an underlead.

With No Real Preference

In general, this common situation is handled by making the least costly preference. This should be accounted for by opening leader, in the context of the hand.

Sometimes, one can, say, with 1082, under the Ace, play the 8, denying tolerance for obvious shift, then follow with the Ten, denying a doubleton. This denies encouragement for both the led suit and the Obvious Shift suit, so this is the way to show either general indifference or perhaps encouragement for a 3rd reasonable suit.

General Carding Scheme

Attitude, in combination with Obvious Shift, is played only:

1.	when following suit to the first time to partner's lead.
2.	when we discard.

Count is used only in five specific instances:

1.	with a doubleton to get a ruff after an A-K lead
2.	at the six-level after a King lead
3.	against no-trump after an Ace lead, or King, if you do it that way
4.	helping partner to hold up and Ace or King
5.	when cashing out and the high cards are known

Suit Preference:

We use suit preference at all other times: e.g. trumps, following mindlessly, etc.
Suit Preference with 3 suits
	Eliminate one, usually the strongest, and give suit preference for the other two

On rare occasions the presentation of very experienced bridge experts and authors are included for the benefit of the reader and visitor. On this rare occasion the interview by BridgeMatters with Mr. Eric Rodwell is included for the benefit of the reader and visitor. The interview was conducted by Glen Ashton and the relevant excerpt is presented here only for the convenience of the reader and visitor. (Note: For the full interview the reader and visitor are requested to follow the included link to BridgeMatters.

The interview was conducted in January 2001 and the main content of the interview was to ask Mr. Eric Rodwell to speak about a number of bidding considerations and issues that might concern many players.

BridgeMatters: Obvious Shift Principle?

Eric Rodwell: I don't really understand it. The idea seems to be the attitude about some other suit seems to be more important than the attitude of the suit that we are leading, and I don't accept that premise. If it is clear that we should be shifting, then it can just be suit preference between the other two suits. If it is not clear, then it should just be talking about the suit we are leading. Then, obviously in some cases if I think I know and I want to tell partner what to do, I could tell him to keep leading the suit even if I am not excited about it or visa-versa.

 

 

If you wish to include this feature, or any other feature, of the game of bridge in your partnership agreement, then please make certain that the concept is understood by both partners. Be aware whether or not the feature is alertable or not and whether an announcement should or must be made. Check with the governing body and/or the bridge district and/or the bridge unit prior to the game to establish the guidelines applied. Please include the particular feature on your convention card in order that your opponents are also aware of this feature during the bidding process, since this information must be made known to them according to the Laws of Duplicate Contract Bridge. We do not always include the procedure regarding Alerts and/or Announcements, since these regulations are changed and revised during time by the governing body. It is our intention only to present the information as concisely and as accurately as possible.