If your client is asking for guidance on the use of the trademark symbol in a press release, you are in a gray area where there's no definitive answer.
The compromise that I like is the one recommended in this blog by Pete Codella, a PR consultant from Salt Lake City whose post I happened upon during an open-ended Google search.
Pete cites this passage from the International Trademark Association:
"The ™, SM or ® symbol need only appear in the first or most prominent mention of the mark. Omission of the ™, SM or ® symbol does not invalidate or compromise a trademark owner’s rights in a trademark. Its purpose is to alert the public to the ownership of the mark, and it is one of the primary ways to affirmatively protect a mark."
In my reading of this guidance, the important part is "or most prominent mention," which is open to interpretation. Is the most prominent mention the headline? Or should the symbol wait for the body of the release where details are explained? You get to choose. There's no rule. Personally, I like headlines that are short and clutter-free, so I'd refrain from using the symbol there, but that's just my personal preference.
Note that you don't need the symbol at all, anywhere:
"Omission ... does not invalidate ... rights," says the ITA.
Does the trademark symbol interfere with SEO? In an open-ended Google search, I couldn't find any evidence that it does, and I found a lot of anecdotal evidence that it doesn't.
I encourage you to read the rest of Pete's 2009 post, which includes his informal survey of PR pros via Twitter, a conversation he had with a lawyer and what the AP Stylebook says, as well as the ITA citation above.
From personal experience as a reporter with The Associated Press, I know that in AP style (the PR industry's adopted style), you capitalize a trademarked name without a TM, SM or R symbol. For example, if the word "Kleenex" was used to mean "facial tissue" in a quote, it would be capitalized, even if the speaker wasn't talking about a Kleenex brand tissue.
Likewise, you Google something (with a capital G) even though you aren't talking about the company but the act of searching. In some parts of the country, people say Coke instead of soda or pop, and the term is capitalized because it's trademarked, even if they are referring to generic soda.
Those two iconic brands -- Kleenex and Coke -- don't use TM or R symbols in their press releases, by the way. I just checked a variety of releases on Business Wire and PR Newswire. However, you will find the R symbol on commercial websites that sell Kleenex and Coke.
Here's what the U.S. Trademark and Patent Office's website says about the benefits of having a registered trademark. It doesn't say how or when to use the symbols, just that they "put people on notice" that you are claiming rights.
Owning a federal trademark registration on the Principal Register provides several advantages, including:
Speaking for myself only, I can add another thought related to the nuanced difference between marketing and PR. It borders on the philosophical, so most of you will want to stop reading here.
The delineation between marketing communications and PR is debatable.
But I think of PR as an effort to generate third-party conversation among people who filter information through their own lenses, thereby lending credibility to information in a way that advertising and brochures cannot.
Credibility comes from the fact that these third parties don't stand to profit or otherwise benefit from an endorsement. No vested interest. I think people tend to listen with their guards down when listening to third parties, whereas they may be more guarded with a speaker who stands to profit from the outcome.
In marketing communications (ads, brochures, company Twitter streams, etc.), it's known that the profiting party is also the source of the information, so "buyer beware." Do I expect a company to volunteer information about a product feature it doesn't offer? No. Brag about bad customer service? No. Reveal hefty repair costs? No.
A TM symbol, in my mind, is the mark of a profiting party. Journalist don't use it. Friends writing to friends don't use it. Only a company with a legal interest in protecting turf uses it.
So you might leave it out of communications where you are encouraging a guards-down conversation.
Press releases fall into the category of marketing communications, not PR, even though it's usually the PR team that drafts and circulates them. A press release goes directly from the company to the public, without first being filtered by a third party. It's like an ad, brochure or company Twitter stream, so "buyer beware."
If I see a TM symbol, my "buyer beware" warning light comes on, even if it was previously off.
My question is this: If a company wants to use a press release to build its relationships with customers and prospective customers, is there any benefit to including the TM symbol? Readers don't find it elucidating or comforting; rather, it may be an annoyance or serve to remind them of the company's self-interest -- guards up!
However, if the press release is meant to be a formal stake in the ground, designating legal territory and excluding competitors, I see the benefit to including a TM symbol. It puts people on notice, as the ITA says. In this case, the primary audience would appear to be competitors and channel or retail partners, not customers.
If the decision were mine, I'd leave trademark symbols out of press releases. But I'm a former journalist, and my opinion may not be representative of the general public's. Maybe people regard the symbol as a mark of authority that boosts their faith in the product -- I don't know.
Either way, I'm comfortable with the ITA's "first or most prominent mention" compromise.