"Is the advertising function," a bright young public relations student recently asked, "a legitimate province of public relations?"

Answer: You bet it is.

Just like traditional communication functions from news releases to speech writing, from lobbying to  social media, the vehicle of advertising -- particularly so-called institutional or public relations advertising -- is, indeed, the province of public relations.

Public relations ads are those that don't promote a product or service or candidate, but rather an idea or  issue or  point-of-view.

Traditionally, public relations ads were a "last resort" – used only after attempts at "free"– or what we call today "earned" – media proved fruitless. The premise was that an item ostensibly "authored by an objective, third party news organization" – be it a feature story,  op ed,  case history or other similar news item – was eminently more credible than a communication for which the sponsor had to pay, i.e. an ad.

On the other hand, if attempts at so-called free publicity failed, then buying an ad – to at least get the story out – was better than nothing.

Today, by contrast, public relations advertising may serve as the centerpiece of a public relations campaign – especially if one has a hot-button issue.

Like gun control, for example.

That's the issue that caused Starbucks CEO Howard Schultz to pay for a "Dear Fellow Americans" issues ad in The New York Times in September, to appeal to Starbucks' visitors to leave their firearms at home.

Schultz's ad, which was followed by nationwide media coverage, social media mania and Schultz sit-downs with TV interviewers, drew enormous attention – some positive, some negative – to Starbucks.

And whether you are a peacenik appreciative of the CEO's message or a pistol-packin' momma enraged by Schultz's squishiness, you've got to acknowledge Starbucks' mastery of the public relations advertising tactic. Here's what the company did right.

· The headline grabbed.

The first requisite of any public relations ad is to make the headline a "grabber."

In Starbucks' case, the straightforward headline highlighted its well-known CEO and his intent to reach out to everyone. It read simply:

"An Open Letter from Howard Schultz, ceo of Starbucks Coffee Company"

Rather than threatening controversy with a headline that took one side or the other, the Starbucks' headline clearly indicated the importance -- and uniqueness -- of the ad, without picking a fight.

Like a caramel macchiato, it invited consumers to sample its palatable product without scaring them off.

· The ad began with a clear  thesis.

A good public relations ad, like an effective op ed, will state clearly the primary point with which it wants to leave readers. Without a clear thesis, the ad is purposeless.

In the Starbucks' case, Schultz lays out his thesis in his first paragraph, clearly and without equivocation. He writes:

"I am writing today with a respectful request that customers no longer bring firearms into our stores or outdoor seating areas."

No question what he is requesting you do, i.e. Leave your piece in the pickup if you're hankerin' for a pumpkin latte.

In so stating, the Starbucks CEO fearlessly opens himself for criticism or at least question from zealous gun owners and Second Amendment purists. So he must immediately back that thesis up with the reasons why.

· The ad backed up the thesis with valid reasoning.

And so Schultz and Starbucks rose to the challenge by rolling out a cohesive, well-reasoned rationale to  corroborate its main point.  

First, he talked about Starbucks' goal to create a "third place" between home and work  for people to relax and enjoy "the peace and pleasure of coffee and community." The existence of guns, he inferred, might disrupt that vision of "a safe and comfortable respite."

Next, he acknowledged that Starbucks is sensitive to local laws in states that allow "open carry" of firearms, and that the company had no intention, therefore, of "requiring" customers to disarm when they approach a barista.

But third, he argued, recent experience of pro-gun activists acting in an "increasingly uncivil" way in Starbucks' stores compelled the company to make its new request for understanding and reason among responsible gun owners.

· The ad closed with a note of commonality.

Just as a speaker should "leave the vivid air signed with his honor," so, too, should a public relations ad close with an appeal to the common values that unite us all.

And so, after stating a straight and sensible explanation of its new policy, CEO Schultz offered up the following soft landing, citing "the better angels of our nature:"

"I am proud of our country and our heritage of civil discourse and debate. It is in this spirit that we make today's request. Whatever your view, I encourage you to be responsible and respectful of each other as citizens and neighbors."

Now that's positive public relations – even if it is an advertisement.