Edit: This is ACBL jurisdiction.
Playing swiss teams, south announced the NT range as 15-17. E-W play precision (opening all 11 HCP hands, and frequently on 10 HCP), and E decided not to make a penalty double of a strong NT even though that was a systemic option. At the end of the auction, N announced the MI, and E called the director. The director took E aside, and was told by E before the opening lead that he would have doubled a weak NT for penalty.
The lead was a systemic club, allowing the contract to make. Either a spade or a diamond lead sets it. At the end of the hand, E called the director back, and explained that he thought his side was damaged because a penalty double of 1N would have made it more likely that partner would find an aggressive lead of her doubleton, especially with trump control.
Everyone at the table is an expert, and in experienced partnerships. How do you rule?