CHAPTER V
THE AUCTION 

PART I
CORRECT PROCEDURE

SECTION ONE
AUCTION PERIOD

LAW 21 - CALL BASED ON MISINFORMATION 

A. Call Based on Caller's Misunderstanding

A player has no recourse if he has made a call on the basis of his own misunderstanding.

B. Call Based on Misinformation from an Opponent

1. Change of Call

Until the end of the auction period (see Law 17E), a player may, without penalty, change a call when it is probable that he made the call as a result of misinformation given to him by an opponent (failure to alert promptly to a conventional call or special understanding, where such alert is required by the sponsoring organisation, is deemed misinformation), provided that his partner has not subsequently called.

2. Change of Call by Opponent Following Correction

When a player elects to change a call because of misinformation (as in 1., preceding), his LHO may then in turn change any subsequent call he may have made, without penalty (unless his withdrawn call conveyed such information as to damage the non-offending side, in which case the Director may assign an adjusted score). (For unauthorised information from withdrawn calls, see Law 16C.)

3. Too Late to Change Call

When it is too late to change a call, the Director may award an adjusted score (Law 40C may apply).