Lead Restrictions
I have what may sound like a stupid question but will ask all the same, otherwise it will keep floating in my head.
When a lead restriction prohibits the player from leading a particular suit the restriction continues to apply as long as the player retains the lead.
But when the restriction requires the player to lead a particular suit there is no mention in the laws that the restriction continues to apply as long as the player retains the lead.
Why ? I haven't been able to figure out the answer.
Comments
I'm not really sure of that either. I guess leading some outside winner then switching to a prohibited suit is considered damaging in a way leading the required suit then switching isn't.
Maybe it's that having led a suit, you can usually work out whether it's a good idea to continue it. Also, if you cash a winner in the suit that may already have helped declarer so there's less need for further rectification.
Whereas, switching to a prohibited suit after cashing an outside winner is likely to be based on the UI that declarer doesn't want the suit led, and is more likely to be damaging to the non-offending side.
If the prohibition was not retained for as long as the player retained the lead, it would often be easy for the player to effectively negate it by leading a different suit and then switching. When the requirement is to lead a suit, it has been fulfilled by leading that suit.
Put another way, declarer has the option to require (what he thinks will be) a helpful lead or to avoid (WHTWB) a damaging lead. In order for that to work as intended, the Law needs to be as it is.
Given the sort of layouts in which declarer is likely in practice to require the lead of a particular suit, it will probably be fairly rare that the defender under restriction will be in a position to cash a winner in the suit.
I think the most common situation where lead restrictions are relevant is when declarer is worried about the defenders cashing quick winners to defeat the contract (but the declarer has easily enough strength to make the contract otherwise), and the rules appear to be geared to that. In such a circumstance, if a defender's irregularity has given their partner on lead more information about their hand than they should have, that information would be particularly useful for defeating the contract (as the defenders will need to cash several tricks without losing the lead).
In this case, a "lead this suit" restriction by declarer is normally intended to allow the declarer to win trick 1, thus gaining control of the hand and making the future of the lead restriction irrelevant. On the other hand, a "don't lead this suit" restriction is intended to prevent the leader from reaching honours in their partner's hand (which the leader presumably knows about as a consequence of the irregularity), and that restriction hasn't done its job until the declarer has gained the lead (otherwise, the leader could just cash a side winner before going to their partner's hand).
Of course, there are other situations in which lead restrictions could be important, but they matter less often and the current rules for lead restrictions work in those cases too, despite the seeming inconsistency.
I guess we've all had situations where the only stopper in a suit is the ability to prohibit the lead of that suit.