Yes you have rights.
FYI. Private establishments can determine who can and cannot be in their establishments (excepting that they cannot discriminate against protected classes of individuals (e.g. race, sexual orientation, etc.). Smokers are not a recognized protected class of individuals. What it was that got you kicked out (your responses to quesitions about the Ecig) isn't clear in your post.
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Generally an establishment that is open to the public is allowed to exclude any person for any reason, as long as the reason is not discriminatory based on the perception that the person is a member of a certain class of person. The most common classes that are pertinent would be, for instance, race, sex, religion, disability, age, or sexual orientation.
Smoking and/or ecig use is not one of the classes for which discrimination is forbidden.
I do not know much about the ecig, but I have heard that it is basically harmless to everybody (except the user of course), so perhaps if you can educate the establishment, then they would allow it. I wouldn't know. It could be that there is a perception that the ecig also produces harmful chemicals.
In any case, it is not unconstitutional under the Federal Constitution for a private establishment to forbid the use of an ecig, and I doubt that Missouri has a State law protecting the ecig. I suspect that the establishment would let you back if you agree not to use the ecig--unless maybe there was something else that occurred at around the same time.
The billl of rights limits what the government can do, not restaurants. Go to another place or better yet do not smoke this device to avoid problems.
Therre may be laws in Mo governing access to public services- that people cannot be denied on the basis of race sex, etc. But, i doubt that you are protected by those as an ecig smoker. for one thing you can opt out of the class byh not smoking. An African American is lodged in an insular and immutable class.I am also accepting what you are saying about the technology. It may not be correct and will certainly be contested in any litigation. Are you ready to hire and pay experts? Contact the manufacturer of your ecig-maybe they are.
I would think though, not knowing the specific Mo laws, that this is a tough case- publicity for the manufacturer and nothing for you. I would deal with it
Thank yo for being considerate of others- that is very kind of you