There are two types of due process challenges to smokefree ordinances- substantive and procedural. The 5th Amendment to the U.S. Constitution states that "No person shall be . . . deprived of life, liberty, or property, without due process of law." The 14th Amendment states that "No State shall . . . deprive any person of life, liberty, or property, without due process of law." Both clauses infer that the government cannot act arbitrarily and that certain procedures must be followed when the government acts.
Substantive due process challenges are raised when there is a belief that the government has acted arbitrarily. These challenges are very similar to equal protection challenges in that courts look to see if a fundamental right has been violated; since no court has ever held smoking to be a fundamental right, substantive due process challenges are very infrequently upheld.
Procedural due process challenges, on the other hand, are more frequently upheld. They are based on claims that the government did not follow their own procedures when passing an ordinance. The violations range from not holding public meetings to not providing notice of meetings. Fortunately, in most cases where a procedural due process claim has been upheld, the acting body repeats passage of the ordinance, this time including the proper steps.