Double is automatic on this hand. It simply says, I am short in diamonds and if you passed 2d with a hand you wanted to penalize 2d with, go ahead. If you bid a new suit over the double, you should have at least a 6-5 hand and no interest in defending. For example, pretend you were not playing negative doubles and you held AKxxx,x,x,AKxxxxx. You open 1c-2d-DOUBLE (penalty)-p: I dont know about you, but I have no interest in defending 2d doubled. My hand is great for offense but poor for defense. The hand I have is an example of a hand id reopen with 2s. On the hand in question, if partner has a penalty pass of 2d, I am pleased to defend. If partner just has a bad hand, I have support for all three suits. Occasionally you may play in a 4-3 fit when it is wrong, but then you pay off.