P17

From Simplex

PRINCIPLE 17: Be very wary about doubling when both opener and responder have taken your bid away. You are usually too weak. (For example, you have a hand worth opening 1♣ but the bidding has already gone (1♦):Pass:(1♠).) Exceptionally you can double at the one and two levels when you have 11+ HCP and you are distributional (e.g. a 5-5 shape or a 6+ card suit).