Gun control in the US is a highly controversial and politicised topic. You have four posts in a row talking about gun violence and gun control in the US. If you weren't aware this was a political topic, that's fine, but I expect there to be no more public posts on the matter. If you have further questions feel free to contact any of the mods by private message.
Talking about laws surrounding guard dog/human aggressive dog ownership is, of course, fine.
For context, I'm American and have lived in several East coast states, including one major city. While many US states do have strong self-defense and property-defense laws, even those only allow the use of deadly force if there is a clear threat to life or property. Someone trespassing by, for example, taking a shortcut through a yard might be breaking the law, but isn't a threat. If a dog attacks them because they're 'intruders' in its eyes, the owner will most likely have a lawsuit on their hands, and the dog will be subjected to whatever the local dangerous dog laws are, depending on the severity of the attack and other factors (like size, breed, history of biting or threatening behavior, etc.).
There are also some circumstances where a dog can be considered a deadly weapon, so if a handler allows or commands a dog to someone (whether the dog is a trained protection dog or not), and it's later found that the handler was not acting in self defense, they could be charged with assault with a deadly weapon or even (in the worst case scenario) second degree murder.
In Norway, where I now live, dogs trained to attack for any reason are banned, as are dogs who are "particularly aggressive, combative or [have] other highly undesirable qualities or behaviour which make them a potential danger for humans or animals." So you can imagine that a private citizen training or encouraging a dog to attack people for any reason is a bad idea here (police and military dogs are exceptions).
In the UK, a dog is considered 'dangerously out of control' and can be classified as a dangerous dog under the Dangerous Dog Act if someone even feels worried that the dog might injure them. There is legal defense if the dog attacks someone who breaks into a house, but not if someone breaks into just the garden.
So that's what I mean when I say you really need to know your local laws if you ever plan on having a dog that attacks people for any reason, whether it's a trained behavior or a case of human aggression. Many countries do not consider it legally acceptable for a dog to attack a human outside of extreme cases of clear and present danger, which means that attack dogs aren't worth the liability for most people in most situations. It may well be different in Romania, I honestly don't know.
