U.S. Customs & Border Protection (CBP) On May 21st proposed revoking earlier rulings that assisted opening knives are not switchblades. The proposed new rule would not only outlaw assisted opening knives, its new broad definition of a switchblade would also include one-handed opening knives and could be easily interpreted to cover most other pocket knives, even simple old-fashioned slip-joints. At this point, one-hand opening and assisted opening knives are 80% of U.S. knife sales (per AKTI industry sources). For most knife companies, they represent all or the majority of their product lines. These are the knives Americans take with them to work and to play everyday.