Go to packing.org, and look for links to your state's weapon laws. There will almost certainly not be a law specifically addressing collapsible batons, but look for words like club, billy, baton, mace, nightstick, and such. ("Mace" is a brand name for a chemical weapon mixture, not a legal term for any type of weapon! Medieval knights carried maces, clubs with weighted ends.) In any event, find the laws for your state, and educate yourself. Or, find a knowledgeable criminal defense attorney to advise you. Your fellow forum members can provide comments, but it will be you who must deal with any legal consequences. I would tell you the same thing if you asked about Texas, where I enforce the law, as there is much gray area in the law regarding impact weapons, and different district attorneys may interpret the same law differently. In Harris and surrounding counties in Texas, a collapsible baton is illegal. YMMV 700 miles away in El Paso. I will say this: a collapsible baton is LESS effective than a solid stick, and a sturdy walking stick or cane is MUCH more likely to be legal just about anywhere than an implement sold as a impact weapon.