Espositori

A conventional euchre wisdom is that the defending team should NEVER lead with trump.  Doing so plays directly into your opponents' strength, and can frequently result is a 2-point hand for them as they take all 5 tricks.

There are some rare situations, however, where leading trump when defending may be more right than wrong.  Here is one such scenario.

You have the lead and the dealer has turned up the .  You pass and the dealer's partner orders it up.  You have two small trump, two suit aces, and a voided suit.

This may be a good place to lead the into the namer.  Many players, knowing they are giving their partner a trump, will order the dealer up with just two high trump in their hand.   The trump namer cannot be certain that his partner can take the first trick.  The might be the only trump that the dealer has.  In fact, you leading it out could very well influence that player into believing you have quite a few trump.  Yet, he can't discount that your partner has one high trump.  He may well burn a bower here ensuring he takes the trick.  You can be sure that the dealer will be unloading that ten of trump on you.

What are his options then if he spends his bower and now has just one more trump?  Even if its the other bower, he won't want to lead it for fear of pulling from his partner, whom he desperately needs help from on this hand.  Even if he has two non-bower trump remaining, if both bowers did not come out on the first trick, he will not want to lead trump because he does not know where the other bower is.  He is most likely to come back in a suit, and you have him covered there.  You have both black aces and you can trump diamonds.  

Your trump lead on defense could set you up to get the blocking trick you need.  If it turns out to be a worst case scenario, and the namer has the other 4 trump - well why the heck did he not go alone?

I want to reiterate that this is would be a very rare situation, but if someone tells you to NEVER lead trump on defense....well, almost!