In filings in response to the suit, Roberts's attorney disputes Carter's version of events and says the firings were not politically motivated. The attorney did not return a call for comment, and Roberts could not be reached.
"All employment decisions involving plaintiffs were constitutional, lawful, not the result of any improper purpose or motive, and not in retaliation for political expression," the sheriff's attorney wrote in the filings.
Roberts said that some of the fired deputies had unsatisfactory work performance and that the campaigning had disrupted the workplace.
U.S. District Judge Raymond A. Jackson issued a summary judgement against Carter and the other plaintiffs in January. In his explanation of the ruling on Carter's claims, he dismissed the argument that a Facebook like is constitutionally protected speech.
"Merely 'liking' a Facebook page is insufficient speech to merit constitutional protection," Jackson wrote. "In cases where courts have found that constitutional protections extended to Facebook posts, actual statements existed within the record."
Facebook took issue with the decision, saying in its filings that likes are the "21st-century equivalent of a front-yard campaign sign." (Washington Post Co. chairman and chief executive Donald E. Graham is a member of Facebook's board of directors.)
Jackson's decision has also drawn criticism from some legal experts. Eugene Volokh, a law professor at the University of California at Los Angeles, said firing government employees for speaking out about matters of public concern is generally unconstitutional.
He said there are some exceptions, such as when a high-ranking employee's political affiliations are relevant to the job, or if the speech greatly disrupts the workplace or diminishes public confidence in the government agency.
In the Sheriff's Office case, Volokh said, Jackson upset a precedent with deep roots in U.S. law.