A black leather jacket (BLJ) can mean different things, depending on who wears it and how they present themselves. Leather is tough -and expensive. The black makes it look somewhat menacing. They were first worn by the military, but then appropriated by others.
Bikers were the first outsiders to take note of the black leather jacket’s utilitarian value, as their inevitable brawls with gravel meant wearing road rash on their leather rather than their comparatively feeble flesh. In 1928, New York designer Irving Schott introduced the “Perfecto,” a zipped and belted hunk o’ hide that reigned as the ideal BLJ silhouette for decades to come. As Schott’s design was originally distributed by Harley-Davidson, the “Perfecto” soon became the saucily soiled flag flown by the most vicious of motorcycle gangs, most notably, the notorious Hells Angels.
Tough, cool, and dangerous. It wasn't long before other groups latched on to the look, and made it their own. Read a short history of the black leather jacket at Collectors Weekly, and peruse a gallery of BLJ images.