Sorry if this ruins your appetite, but ER 1.6 applies to your dinner-table conversations.
Consider this scenario: You're representing Mr. Big Deal Athlete in his high-profile divorce. The spouses accuse each other of salacious conduct and domestic abuse and are fighting over lots of assets. The litigation is hot and heavy and, thanks to an attentive news media, your teenagers have finally realized that you -- their otherwise uncool parent! -- represent Mr. Big Deal. At the dinner table, they interrogate you. What's Mr. Big Deal like? Did he really have an extramarital affair with Mrs. Big Deal's sister? Did Mrs. Big Deal really have an extramarital affair with one of Mr. Big Deal's teammates and did that affair produce one of the Big Deal kids? Why didn't you tell us before that you represent Mr. Big Deal? <Sigh> You're happy your teenagers are communicating with you, so you respond, giving them your personal impressions of Mr. Big Deal (nice guy, full of himself but yet bizarrely naïve, extremely talented, lots of earning potential) and confirming and denying (as appropriate) the extramarital affairs information based on what you and your opposing counsel have put in court filings.
Here's the thing: ER 1.6 doesn't include an exception for your dinner-table discussions with your kids and spouse.
To refresh your memory: ER 1.6(a) prohibits a lawyer from disclosing “information relating to the representation of a client” unless the client gives informed consent, the disclosure furthers the representation or some specific exception applies. That's all information, not just attorney-client-privileged information; not just juicy non-public but not privileged info your client tells you to keep secret. It even includes information publicly available....like what you and opposing counsel have put in filed pleadings. ER 1.6 cmt  ("applies...to all information relating to the representation, whatever its source").
You might have forgotten about that last sentence.
I know what you're thinking: ER 1.6 can't possibly prevent a lawyer from talking about or repeating information that's out there in public.
Yes, it can, and it does. It all depends on why you're talking about that information. Sharing with your family or friends is not one of the permissible reasons for disclosing information.
Remember several years ago how the public didn't know that Harry Potter author J.K. Rowling had written "The Cuckoo's Calling" thriller under the pen name Robert Galbraith? The public didn't know until a lawyer with the London firm that represented Rowling told his wife's friend, who then tweeted the information. (That lawyer was fined and reprimanded; the firm paid damages to Rowling.)
No matter whether the information is truly secret -- such as Robert Galbraith's identity -- or not secret -- what you wrote in a filed and open-to-the-public pleading -- the question is whether you, as the lawyer, are allowed to disclose the “information relating to the representation of a client." This does indeed mean that everyone else in the world can gossip about or use for marketing public information relating to a client's legal matter. Except for you. Because you're the lawyer. It's as simple as that.
Possible changes to ER 1.6
Last year, the Supreme Court convened a committee to look at a variety of Ethical Rules and what I like to call "ability-to-practice rules." The rule-change petition that resulted from that committee's efforts explained that the court established the committee "in recognition that the changing practice of law in the last decade poses new ethical questions that necessitate review of certain court Rules governing the practice of law” and tasked it “with examining and updating the current Rules to ensure that the public is protected and the Rules do not impose unnecessary barriers to the delivery of legal services.” The court has already adopted most of the committee's recommendations but one proposal -- revising ER 1.6 -- is still in play.
The committee proposed revising ER 1.6(a) to redefine “confidentiality” to mean, in general, information either (1) truly confidential, as that word is generally thought of, or (2) even if not confidential, of such a kind that disclosure would harm the client’s interests. Here's the committee's actual proposed rule change:
The court committee's proposal harkens back to how the Code of Professional Responsibility (in effect in Arizona until February 1985, when we adopted the Rules of Professional Conduct and ER 1.6) treated confidentiality. DR 4-101 of the Code of Professional Responsibility required lawyers to keep clients' confidences and secrets. Unlike the current ER 1.6 standard of “information relating to the representation of a client,” DR 4-101 defined "confidence" as information protected by the attorney-client privilege and "secret" as "other information gained in the professional relationship that the client has requested be held inviolate or the disclosure of which would be embarrassing or would be likely to be detrimental to the client." In other words, the Code of Professional Responsibility universe of information lawyers had to keep confidential was narrower than that of the current Rules of Professional Conduct.
The Supreme Court held onto the committee's proposal and instructed its staff attorneys to come up with an alternative. Here's that alternative:
The staff attorneys' alternative keeps ER 1.6's current broad umbrella but adds a circumstance under which lawyers may disclose otherwise protected information. The problem with this approach is defining what is "generally known." Does that mean information theoretically available to anyone as a public record? Or does it mean information that's appeared in the news media?
The Supreme Court is scheduled to consider the ER 1.6 proposal on December 15.
Meantime, we all should be circumspect about our dinner conversations.