The TD videos on the subject is clear, however, several occasions I have been called when opponent has a trump. The last one Declarer had Qxx, defender 10.
When I was an opponent recently a similar situation arose when Declarer had J, 3 & 2 and I had the ten. He clalmed saying "I have the top three trumps", so I called the Director who gave Declarer the 3 tricks saying "it is logical that he would have played the J first".
I saw on another occasion the same director ruled the other way. Thoughts anyone?