Kate had support for me, but I had support for East

The majority of tournament players in North America use support doubles. A common example is this auction:

   West    North   East   South
   1♣     Pass    1♥    1♠
   ?

A raise to 2♥ shows four-card support and double indicates a three-card raise. The rationale is that distinction is more important than the occasional penalty double at the one level.

When players first started using this treatment, I remember that some didn't like it. "If I use the red card, it means they are doing down," they said.

Using support doubles doesn't give up a penalty double. If West passes (as above), East will often be able to reenter the auction with double to say, "I have 9 or more points, partner, let's don't sell out." West can obviously pass, in that case, with a club stack.

Another advantage is that you can penalize them when the responding hand has the trump stack, as Kate and I did in Philadelphia at the World Bridge Series (both sides vulnerable):

                ♠ J
                ♥ K 7 6 5
                ♦ A 5 3
                ♣ A 8 7 6 2
♠ 10 7 6 5 3                   ♠ K Q 2
♥ J 10 3 2                     ♥ Q 4
♦ J 10                         ♦ 8 6
♣ 5 4                          ♣ K Q J 10 9 3
                ♠ A 9 8 4
                ♥ A 9 8
                ♦ K Q 9 7 4 2
                ♣ ---
    West    North    East    South
                             1♦
    Pass    1♥      2♣      Dbl
    All Pass

I passed the support double. Yes, Kate had support for me, but I had support for East, haha.

Kate (South) led the ♦K Q, and paused to think. She knew I had three diamonds, only four hearts and (likely) five clubs. That left me with a stiff spade. She led the ♠A and another as I ruffed. I played the ♥K and another to her ace and she gave me a second spade ruff. I still had the ace of trumps to win, and that was down 800. I wonder why they aren't all this easy.

Yes, I was lazy. I should have overtaken the second diamond and shifted to the spade myself. Also, notice that East had a perfectly normal overcall.

A few pairs bid and made 6♦, but we scored 89.6% on the deal. I'm wondering why more pairs didn't have the same result. Maybe South rebid his diamonds instead of making the support double.

You can see the hand record and results if you go here, and look for board #7.