[logicalmind]

It's all about negligence and what you can prove in a court of law (or settle for in arbitration these days). A person taking an open flame and leaving it unattended or not monitoring it, is negligent in the eyes of most people (aka jurors). There is a reasonable expectation that an open flame is going to cause a fire if expose to combustable material.

But what about a person dropping a lit cigarette on a couch (either sleeping or not). A cigarette isn't an open flame so the above doesn't apply. Is there a reasonable expectation that a lit cigarette would cause a couch to catch on fire? If there is, and a jury agreed, then the person who dropped it would be negligent.

But I would expect said person's lawyer to show that a standard cigarette dropped on a couch would not and could not cause a fire. But cigarettes manufactured by company X are treated with chemical Y in order to make them non-standard. And while the client may be partially negligent (for dropping the cigarette or falling asleep), the manufacture is also partially negligent for (knowingly) adding fire sustaining chemicals to an otherwise standard cigarette. If the cigarette manufacturer could prove that a standard cigarette would catch a couch on fire, and the knowledge of this was obvious to a standard person, then the person would be 100% negligent.