Following a link from Sebastian on efforts to block importation of common knives I found this:
Our interpretation of 15 U.S.C. § 1241(b) and 19 CFR 12.95(a)(1) is supported by case law. In Demko v. United States, 44 Fed. Cl. 83, 88–89 (Fed. Cl. 1999), the Court of Federal Claims, in analyzing a regulation regarding the grandfathered sale of ‘‘street sweeper’’ shotguns, recited the following interpretations of the word ‘‘or’’ as used in statutes and regulations:
‘‘Generally the term ‘or’ functions grammatically as a coordinating conjunction and joins two separate parts of a sentence.’’ Ruben v. Secretary of DHHS, 22 Cl. Ct. 264, 266 (1991) (noting that ‘‘or’’ is generally ascribed disjunctive intent unless contrary to legislative intent). As a disjunctive, the word ‘‘or’’ connects two parts of a sentence, ‘‘but disconnect[ s] their meaning, the meaning in the second member excluding that in the first.’’ Id. (quoting G. Curme, A Grammar of the English Language, Syntax 166 (1986)); see Quindlen v. Prudential Ins. Co., 482 F.2d 876, 878 (5th Cir. 1973) (noting disjunctive results in alternatives, which must be treated separately). Nonetheless, courts have not adhered strictly to such rules of statutory construction. See Ruben, 22 Cl. Ct. at 266. For instance, ‘‘it is settled that ‘or’ may be read to mean ‘and’ when the context so indicates.’’Willis v. United States, 719 F.2d 608, 612 (2d Cir. 1983); see Ruben, 22 Cl. Ct. at 266 (quoting same); see also DeSylva v. Ballentine, 351 U.S. 570, 573, 100 L. Ed. 1415, 76 S. Ct. 974 (1956) (‘‘We start with the proposition that the word ‘or’ is often used as a careless substitute for the word ‘and’; that is, it is often used in phrases where ‘and’ would express the thought with greater clarity.’’);
Emphasis added.
They go on to conclude:
In New York Ruling Letter (‘‘NY’’) G83213, dated October 13, 2000, CBP determined that ’’a folding knife with a spring-loaded blade [which could] be easily opened by light pressure on a thumb knob located at the base of the blade, or by a flick of the wrist’’ was an ‘‘inertia-operated knife’’ that ‘‘is prohibited under the Switchblade Act and subject to seizure. See 19 C.F.R. §12.95 (a)(1).’’ In NY H81084, dated May 23, 2001, CBP determined that 18 models of knives ‘‘may be opened with a simple flick of the wrist, and therefore are prohibited as inertial operated knives.’’ In HQ 115725, dated July 22, 2002, CBP determined that a ‘‘dual-blade folding knife’’ in which the ‘‘non-serrated blade is spring-assisted [and] is opened fully by the action of the spring after the user has pushed the thumb-knob protruding from the base of the blade near the handle to approximately 45 degrees from the handle’’ ‘‘is clearly a switchblade as defined in § 12.95(a)(4) (Knives with a detachable blade that is propelled by a spring-operated mechanism and components thereof.)’’
Again, emphasis added.
So now it appears you can be prosecuted for possession of a switchblade knife if the spring holding the blade shut is broken. It's the Olofson case applied to knives. And it appears they are pushing toward calling any knife you can open with one hand as a switchblade. And who does the testing to determine if whether the knife "may be opened with a simple flick of the wrist"? Will the Bureau of Alcohol, Tobacco, Firearms, Explosives, Knives, and Sharp Pointy Sticks have labs full of technicians with calibrated wrists such that you can send your knife in for periodic testing to make sure the retention spring hasn't gotten too weak?
I have to wonder if a Second Amendment test case can't be brought up on knives in one of the states in the 9th Circuit where incorporation has already been made (or in D.C.). What is the government going to say, "Sure, the Second Amendment guarantees you the right to carry a handgun to defend yourself but we can't let people own something as dangerous as a knife in their own home! Think of the children!"? Actually, they might. But it would be pretty funny seeing them laughed out of court when they do.
Update: I just figured out how to open my Spyderco Delica "with a simple flick of the wrist". I think I can use the same method with nearly any folding knife. It's easier and faster to open my Delica one-handed the way it was intended but still it appears that that if the criteria is "may be opened with a simple flick of the wrist" to define it as a "switchblade" and hence it's outlawed then it's game over man. We then will have to go to the courts to be able to carry a folding knife.