[pran]

 pran, on 2018-May-17, 02:11, said:

A fundamental principle which is often overlooked is that a deviation from disclosed agreements/understandings is (legally) a psyche only if partner has no more reason than the opponents to be aware of the deviation.

 blackshoe, on 2018-May-17, 14:23, said:

I think this is a mis-reading, or perhaps a mis-stating of the law. That phrase applies to all deviations, not just psychs. Your point seems to be that if the bidder's partner is aware of the possibility, then it's not a psych. That's true, but if he's aware of a particular deviation, then it's not a deviation either.

 pran, on 2018-May-17, 02:11, said:

So stating that "partner has a tendency to psych in these positions" (or words to similar effect) automatically makes that partner's call included in the partnership's agreements/understandings and no longer a legal psyche.

 blackshoe, on 2018-May-17, 14:23, said:

Precisely. Same for deviations that aren't "gross".

I do believe that we really fully agree here.

Personally I am not comfortable with the term "psyche" as denoting a "gross" rather than a "minor" (deliberate) deviation from partnership understandings/agreements.

Law 40C1 does not distinguish, but instructs the Direector to handle either case in the same way.

[pescetom]

 pran, on 2018-May-17, 02:11, said:

So stating that "partner has a tendency to psych in these positions" (or words to similar effect) automatically makes that partner's call included in the partnership's agreements/understandings and no longer a legal psyche.

This was perfectly clear.

 pran, on 2018-May-17, 02:11, said:

A fundamental principle which is often overlooked is that a deviation from disclosed agreements/understandings is (legally) a psyche only if partner has no more reason than the opponents to be aware of the deviation.

 blackshoe, on 2018-May-17, 14:23, said:

I think this is a mis-reading, or perhaps a mis-stating of the law. That phrase applies to all deviations, not just psychs. Your point seems to be that if the bidder's partner is aware of the possibility, then it's not a psych. That's true, but if he's aware of a particular deviation, then it's not a deviation either.

Not sure I completely follow either of you here.
Unless one has strange agreements, then a pysche will be a deviation, but not all deviations are psyches.
And one can be aware of a deviation which remains a deviation: but so can his opponents if agreements are correctly disclosed.

[barmar]

The point of the qualifier "gross" in the definition of a psych is to distinguish them from more common situations where a player chooses to be a little aggressive or conservative, or just can't find a perfect bid so he chooses the least lie.

The Laws don't really distinguish requirements based on the amount of deviation. But I think opponents are generally aware that most agreements are approximate, and players frequently make judgement calls on borderline hands, so it's not as necessary to disclose the possibility of small deviations. But they're not likely to expect gross deviations; if your partner does this often enough that you adjust your bidding to account for it, as on this hand, then the opponents are definitely entitled to disclosure.