SnickF,
I think "Halt" products are legal in most states. Certainly they are in Oklahoma. But I hate carrying extra stuff with me when I run.
When running, I am aware that I am "unarmed" except for my attidue. I normally have some situational awarness about possible dog ambush spots. As I come to those, I will pick out a rock for each hand. I don't like very big ones. As the dog or dogs make their run up I launch the first rock outside any reasonable distance for accuracy. But, I make sure it lands in front of the lead dog and skips a few times up to him. That often stops the whole thing. At least they figure out that I am not so easy a mark. The second rock needs to be saved in the event the dog/s come on and ideally and the ground quickly searched for more rocks. This time the throw needs to sharp and true. I wait until the last moment to ensure a strike. In any event, it needs to be followed up with a commitment to chase, holler and make funny noises at the dog/s.
All this is a lot easier if you are on a gravel road like we have around here. When I run on asphalt roads with no ammo, I carry my rocks a lot farther for protection. Sometimes a stick is all that is available, though, and I will carry that.
Still, however, I think the most important thing to have with you is an "attitude." "Here, little doggie. Come here a little closer, so I can smash you with my shoe, kick you in the gut and stomp on your head." Somehow, they figure out that I'm not kidding and that if given the opportunity I will truly grab them by their neck and carry them bodily barking and kicking and scratching and snapping over to a t-post fence post and impale them on it like a gutted catfish. They leave me alone for the most part.
All this interrupts an otherwise peaceful run, and doesn't make me proud when I go to Sunday School, but it has served me well while training.
Tyson