This article proposes an electrical analysis of a new defect mechanism, to be named as b-open defect, which may occur in nanometer technologies due to the use of the Self-Aligned Double Patterning (SADP) technique. In metal lines making use of the SADP technique, a single dust particle may cause the simultaneous occurrence of a bridge defect and an open defect. When the two defects impact the same gates, the electrical effects of the bridge and the open combine and exhibit a new specific electrical behavior; we call this new defect behavior a b-open. As a consequence, existing test generation methodologies may miss defect detection. The electrical behavior of the b-open defect is first analyzed graphically and then validated through extensive SPICE simulations. The test pattern conditions to detect the b-open defect are finally determined, and it is shown that the b-open defect requires specific test generation.