Why did the Constantine TV show go out of its way to never show the titular character smoking?

Question

In the 2014 TV show Constantine, John Constantine is a cigarette smoker, just like his comic book counterpart. However, we rarely (never?) see Constantine actually smoke (i.e. breathing in and out the cigarette smoke). For instance, he will pull out a cigarette and lighter, but then get distracted before actually smoking and put it away. Even in the crossover with Arrow, we see Constantine stamping out a cigarette, but not actually smoking.

Why is this? Did actor Matt Ryan not want to smoke onscreen? Is there some sort of rule that smoking can't be portrayed on a television show? Why did Constantine go out of its way to never show the titular character smoking?

Answer 1

In the following article from Entertainment Weekly 'Constantine' team on why NBC character isn't bisexual, smoking cigarettes, the producers claim they could not glorify the character’s smoking due to network content standards.

For the show, producers say Constantine is indeed a smoker … just don’t expect to actually see him smoking. Producers say there’s not much they can do about this due to network content standards.

“He is a smoker in the show, we’re not shying away from it, but we’re not glorifying it,” said executive producer David S. Goyer.

Answer 2

From Wikipedia:

The show remains more faithful to the source material than the 2005 film, although on-screen depiction of Constantine's chain-smoking habit was said to be curtailed because of broadcast television restrictions (the network eventually becomes more lenient and John is shown smoking on screen in later episodes)

Link to the referenced article: Constantine Will Not Be Allowed to Smoke on TV.

In an interview with Collider, pilot-episode director Neil Marshall was asked point-blank about the detail and answered

"No we're not. It's the one thing, a compromise I guess. On network it's the one thing you can't smoke on network. That's one of his character traits. We're working around that. We're trying to get aspects of it in there as much as possible. We'll see."