Today we will discuss breaks in tempo in the auction. Bridge is a partnership game, but partners may only convey information to each other by the calls they make. No other conveyance of information is allowed. Ideally all bids would be made in the same tempo, but bridge requires thought and some situations may require significant thought. When confronted with a difficult problem it is natural and perfectly legal to take time to evaluate your options. The problem is that when you take time, you send a message to the table that you have a problem. The laws of bridge state that the opponents may draw inferences from a players pause for thought, but they do so at their own risk. The partner of the person breaking tempo is prohibited from taking any action demonstrably suggested by the break in tempo when another logical action is available.
Competitive auctions and preempts often lead to breaks in tempo. The stop card is used to alert your left hand opponent that you are going to skip one or more levels of bidding, and that he should pause 6 - 10 seconds whether or not he has a problem. The stop card is for the protection of the skip bidder's left hand opponent and must be consistently used. It may not be used, for example, with weak jumps but not strong. Whether a stop card is used or not, the next player is to pause and appear interested in the auction before making his call.
In any auction when a player takes extra time before making a call, his partner is on notice that there were other action(s) which might have been taken. If a break has occurred, the opponents should call the director to state there was, in their opinion, a break in tempo. This is not an accusation of anything improper having happened. The director will do his best to establish the facts and will caution the partner of the person who allegedly broke tempo not to choose from reasonable options any action suggested by the break. Best practices are to acknowledge to the table if your partner has had a noticeable break in tempo, in which case the director need only be called if at the end of the hand, opponents feel they were damaged by the break.