WASHINGTON—An Arizona newspaper had the legal right to fire a reporter over the content of messages he was posting to Twitter, a federal labor board has found.

In September 2010, the Tucson, Ariz.-based Arizona Daily Star fired its crime and public safety reporter for repeatedly publishing what the paper deemed to be “unprofessional and inappropriate tweets” via his Twitter account, including references to his position at the paper and links to its website, according to an advisory memo the National Labor Relations Board issued last month.

The board found that the unnamed reporter’s termination did not violate a provision of the National Labor Relations Act that protects communications by employees as long as they relate to—or seek to involve other employees in a discussion of—working conditions or employment terms.

According to the board’s memo, in January or February 2010, the reporter posted a snide remark about the Daily Star’s copy editors concerning headlines that had run in the sports section. The paper’s editors reprimanded the reporter and told him he was prohibited from “airing his grievances or commenting about the Daily Star” in any public setting.

Several months later in 2010, the reporter posted several messages related to his work as a crime reporter, including:

• Aug. 27: “You stay homicidal, Tucson. See Star Net for the bloody deets.”

• Aug. 30: “What?!?!? No overnight homicide? WTF? You’re slacking Tucson.”

• Sept. 10: “Suggestion for new Tucson-area theme song: Droening (sic) pool’s ‘let the bodies hit the floor’.”

• Sept. 10: “I’d root for daily death if it always happened in close proximity to Gus Balon’s.”

• Sept. 10: “Hope everyone’s having a good Homicide Friday, as one Tucson police officer called it.”

On Sept. 21, 2010, a local television news station posted a tweet containing a misspelled word, which the reporter lampooned in a tweet of his own, calling the station’s staff “stupid TV people.” The following day, the news station’s producer emailed the Daily Star’s staff to complain about the “unprofessional” tweet.

“What I take issue with is calling TV people stupid,” the station’s producer said in an email to the Daily Star’s reader advocate desk. “Clearly (he) is entitled to his opinion, but I feel since this particular account is affiliated with the Star, a tweet like that becomes unprofessional.”

The reporter was suspended and then fired on Sept. 30. In its termination letter, the paper’s publisher and editors said they “have no confidence that you can sustain our expectation of professional courtesy and mutual respect.”

The newspaper is owned by Davenport, Iowa-based Lee Enterprises, Inc.

In its advisory memo declining to pursue the fired reporter’s complaint, the NLRB noted that even though the Daily Star did not have an internal policy specifically addressing social media communications, which could have made the reporter’s termination illegal had he complained about working conditions or employment terms, its actions were not illegal because the messages themselves were not protected by the law.