Hello all, I'm from Long Island but do work in the City.
I am a retired NYC Police Officer of 20 years. 15 of those years I worked in the transit system.
With regards to vaping on the subway, here are my thoughts and I highly reccommend that you do not provoke the police on the issue.
The NYC Transit system does not follow the NYS "No Smoking Ban". Instead they have their own set of rules called NYC Rules and regulations. The "No Smoking" rules fall under section 1050.7 (Disordelry Conduct) subdivision B. It reads as follows:
Section 1050.7
Disorderly conduct.
No person on or in any facility or conveyance shall:
(B) smoke or carry an open flame or lighted match, cigar, cigarette, pipe or torch;
So far so good right?
Now let us proceed.
The Transit Adjudication Bureau which handles the fines and summonses issued for NYCRR Violations is a KANGAROO COURT. That means that to fight a summons you need to go in there with OJ Simpson type lawyers. I am talking from my 15 years experience working as a Transit Cop.
Now let's look at the definition of "Smoking" and "Smoke" as per dictionary.com. Pay attention to the wording in BOLD
SMOKE
noun 1. the visible vapor and gases given off by a burning or smoldering substance, esp. the gray, brown, or blackish mixture of gases and suspended carbon particles resulting from the combustion of wood, peat, coal, or other organic matter.
2.something resembling this, as vapor or mist, flying particles, etc.
SMOKING
verb (used without object)
11.to give off or emit smoke, as in burning.
12.to give out smoke offensively or improperly, as a stove.
13.to send forth steam or vapor, dust, or the like.
14.to draw into the mouth and puff out the smoke of tobacco or the like, as from a pipe or cigarette.
Now....
Based on this definition from the dictionary, you may be found guilty in that kangaroo court.
Anybody from TAB court can pull out a dictionary and focus on the definitions as stated above and technically, vaping your e-cig on the subway, you can be found guilty and issued a fine.
Now let's talk about the cops. NYC Transit cops are a rare kind. If you gave them a hard time or even argue the case with them, they can and will give you a summons and tell you to plea your case in court. Technically all they need to do is state that they observed what appears to be smoke. It will then be your case to argue and fight in court. They will not argue or debate with you in the subway about it.
Many of these cops are young, fresh out of the Academy and don't know any better. However, I will highly reccommend that if they ask you to put it out, then do so. Feel free to educate them on the e-cig but comply with their request. If you start to argue with them about it, then they can order you to put it out. If you continue to argue with them then you are taking the chance of either getting a summons or locked up (Yes they can arrest you on minor violations). If you cause a scene and argue with him/her, now you can get summoned or locked up for disorderly conduct because now at this point you are disobeying a lawful order and causing public alarm.
Just because one officer says it's ok to vape does not mean another is going to say it's ok also.
It is in my opinion to all NYC Vapors to not provoke the cops and be the first test case.
I am always in the City conducting training sessions and use the subways and I don't vape on the subways. Sure I can vape, and when questioned by an officer, show my NYPD ID Card and there will be no further questions asked, but I won't even think about it.
The NYC Transit system and it's rules have many "grey" areas that can be interpreted in different ways.
For example, did you know that you can get a summons for carrying a open liquid container? That means that technically you can get a summons for carrying a cup of coffee or even a container of orange juice or an open can of soda! Yep it's true.
So in conclusion, I am just offering some advice. You can feel free to do what you want, however I would not want to be the first test case and God forbid get my stash confiscated because it appears to be some type of parapenelia.