Hey, All:
Thanks for a fascinating discussion about one of my favorite topics.
With regard to a Z-Cut-style defensive knife, the Bastinelli Mako design--and many of his other designs--already comes very close:
https://www.tacticalelements.com/bastin ... ixed-mako/.
As an avid knife and switchblade collector, I have done extensive research on U.S. federal law. According to AKTI, "The Federal Switchblade Act –
is the only federal knife law other than laws about knives in federal facilities. The 2009 Amendment clarified assisted-opening knives are not illegal switchblades."
The Federal Switchblade Act was created to prohibit interstate commerce of switchblades, but was later interpreted by U.S. customs to also apply to the importation of switchblades. Later still, customs interpreted balisongs as falling under the descriptive guidelines of the law and applied it to them as well. The forces that motivated those customs decisions are one of the knife industry's dirty little secrets...
The U.S. Customs regulation that defines the categories of knives that cannot be legally imported is 19 CFR § 12.96. It reads:
Imports unrestricted under the Act.
(a) Common and special purpose knives. Imported knives with a blade style designed for a primary utilitarian use, as defined in § 12.95(c), shall be admitted to unrestricted entry provided that in condition as entered the imported knife is not a switchblade knife as defined in § 12.95(a)(1). Among admissible common and special purpose knives are jackknives and similar standard pocketknives, special purpose knives, scout knives, and other knives equipped with one or more blades of such single edge nonweapon styles as clip, skinner, pruner, sheep foot, spey, coping, razor, pen, and cuticle.
(b) Weapons with fixed blades. Importations of certain articles having a fixed unexposed or exposed blade are not within the prohibition of 15 U.S.C. 1241 through 1245. However, upon release by Customs, possession of these admissible articles which include such weapons as sword canes, camel whips, swords, sheath knives, machetes and similar devices that may be capable of use as weapons may be in violation of State or municipal laws.
[T.D. 71-243, 36 FR 18860, Sept. 23, 1971, as amended by T.D. 90-50, 55 FR 28192, July 10, 1990]
There is no federal law that prohibits the importation of double-edged knives. When I worked for BlackHawk, I designed the UK-SFK--the issue dagger for the British SAS. It and several other double-edged knives we produced were produced in Taiwan and legally imported into the U.S. in full compliance with all applicable customs regulations (paragraph b above). Many other knife companies, including Boker and Cold Steel, legally import double-edged knives in exactly the same way.
With all that said, the actual consumer market for double-edged knives is much more limited than the market for single-edged knives. The reason is that the carry--and sometimes mere possession--of double-edged knives, dirks, daggers, etc. is prohibited by many state and/or municipal laws. This fact is mentioned in the Customs regulation quoted above. Although compliance with applicable laws is always the responsibility of the consumer, since the market space is more limited, the commercial potential is also more limited. For that reason, producing double-edged knives isn't always a wise or profitable business decision.
So what about all the new-production foreign-made switchblades and balisongs that are being openly sold on the Internet and through dealers? They are being imported in violation of the Customs regulation. It's that simple.
Stay safe,
Mike