“A Billion Lives” is the kind of documentary that seeks to get you all worked up about an injustice but leaves you feeling as if there were nothing you could do about it. It’s also the kind of documentary that asks you to accept one set of experts’ version of things and reject another’s, when you suspect that disinterested parties are probably rare on either side.

The film, by Aaron Biebert, promotes vaping and e-cigarettes as tools for helping smokers who want to quit. Its title is said to refer to one projection of how many lives will be lost in this century because of smoking.

Mr. Biebert employs the standard documentary format — talking-head experts mixed with personal stories — to explain why vaping is safer than cigarettes and to sketch a vast conspiracy that keeps these products inaccessible and, in some places, illegal. The tobacco industry, of course, is his conspirator in chief, since it doesn’t want its profits cut, but the players also include governments, medical professionals with a vested interest in smoking-cessation prescription products, even anti-cancer charities.

It’s a net broadly cast and woven of implications rather than of indisputable evidence, but — especially given the tobacco industry’s credibility problems — you’ll probably be inclined to think there’s some truth to the film’s allegations. And certainly you’ll feel for the smokers who testify movingly of being eager to try anything that might help them shake their habit. The film, though, doesn’t have any suggestions as to what the average viewer might do to help break the supposed conspirators’ blockade.