Law 57A said:
When a defender leads to the next trick before his partner has played to the current trick or plays out of turn before his partner has played, the card so led or played becomes a major penalty card...
So what happens if East (a defender) is on lead, leads a card and before South has played, West plays a card? This doesn't come under 57A and I couldn't find any other relevant laws (all the "out of turn" laws referred to leads, not plays subsequent to a lead).
I guess having no penalty prescribed in Law for this is OK from declarer's point of view because he can pick his card according to both defenders' cards (say West put the Ace on the trick, South could play small where he would otherwise finesse). My worry here is that, like playing a card with emphasis if you want partner to get the signal, this is tramsitting UI (e.g. quick card = likely singleton). Also players shouldn't really see playing out of turn as an "OK thing to do" because there's no penalty.
Did I miss a Law, or are people allowed to play out of turn?
ahydra