Criminals sometimes obtain guns on the black market from people who purchased them under legal license but are corrupt and sell them to gun dealers. The gun trade and corruption are how violence is spread to other parts of the world and back to the United States. Banning guns worldwide would certainly deliver a major blow to the black market, although it wouldn't stop. Black markets are just one way to get a gun under the radar. Due to the gun trade, we do not know what other associations exist around the world. The opposition might say that if guns are banned, how are innocent civilians supposed to defend themselves? Guns aren't the only self-defense weapon they can use. There are self-defense classes that women and men can take and there are things like pepper spray that might work when you're trying to defend yourself. Not having a gun for self-defense would prevent people from hurting others and ending up in prison for many years if they killed someone in self-defense. Some people feel safer carrying a gun, but it could lead them to take the law into their own hands.