Here's a question I've considered since high school, have done considerable research on, have asked law enforcement about, and have received many answers to. Is it legal to possess and/or sell balloons full of marijuana smoke? I need to know this because I would never do anything illegal.
(ATTORNEY GENERAL'S WARNING: Contains information that may cause incarceration.) What you really mean is you don't want to be arrested. Well, same here, so even though this smells like a duck, quacks like a duck, and follows you around the park begging for bread like a duck, it's not a duck. Or legal advice. Only a bona fide lawyer can dispense that. If one day you're jammed up by the fuzz, forget you ever heard of me. My attorney and I are already having trouble recalling you.
I posed your little scheme to a sampling of keen legal minds, checked with the state attorney general's office, perused the state health and safety codes, and consulted a criminalist for scientific details. Near as I can tell, you'd be breaking no existing marijuana sales or possession laws by selling smoke.
Marijuana laws require evidence of some measurable amount of the plant itself. Marijuana smoke, of course, contains the active ingredient THC, and the presence of THC in your balloons could be established in a lab by gas chromatography. And gasses can be weighed. So with enough analysis, it's theoretically possible to quantify the THC in your inventory. But since, strictly speaking, it's not in the form of plant material, you seem to have skated around the law. There's a chance you might be arrested for selling paraphernalia; balloons are specifically listed in the state codes as potential drug gear.
Because balloons gradually leak their contents, you'd have some interesting inventory problems, but that also might work in your favor when it comes to evidence. By the time your balloons arrive at the lab, there's no telling if enough THC would be left on the inside to identify. And don't forget - America being the capitalistic wonderland that it is, with our penchant for taking a small idea and force-feeding it to grotesque proportions - you're sure to inspire flashy competition: crack, heroin, crystal, PCP - all the smokeables.
There's really no final answer to your question because the issue of selling smoke apparently has not been tested in court. You might run up against an eager beaver D.A. who wants to make the argument that the intent of the marijuana laws is to keep people from coming under the influence of the drug, therefore the physical form doesn�t matter. My sources considered that a pretty shaky argument. But until you're willing to put your entrepreneurial butt on the line, we won't know for sure.