I am not sure whether in CA or in any other state the private employer has to provide an area for smokers to use. That is a good question and hopefully one of the other attorneys or non-attorneys will know the answer.
My take on it is that the private employer is stating that said activity may never take place on their property at any time for any reason. I would argue that such a blanket policy is a denial of individual liberties. The reasoning is that tobacco and its use is a lawful product and activity, reardless of how politically incorrect it is, or how villified it is by Bill Clinton & gang.
Moreover, the employer is allowing its employees to park their cars on its property. Granted the use of the parking space is to allow the employee easier, quicker, and safer ingress and egree to the work area. Still, any tobacco use by an employee in his car on his time is a lawful and constitutionally protected act. That act is no different, constitutionally, than the employee listening to his radio (regardless of what station), or reading a book (regardless of what kind), etc. So the employer has no authority to ban certain constitutionally protected activities by its employees without showing a huge need for such and without the employees knowing consent to that denial.
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Mark B. Replogle