A recent article published by the LA times reports the US Supreme Court made a 6–2 ruling in favor of a government employee who was wrongfully terminated for what was determined to be protected speech.
The crux of the issue lay in the fact that previous court rulings had established a small loophole where employees, even in public sector jobs, could not sue for retaliation if the employer punished them for perceived political beliefs.
The third circuit court of appeals made a prior ruling determining that demoted employees can sue for retaliation only if they could point to an “actual, rather than perceived, exercise of constitutional rights.” (ibid.)
In this case the employee facing retaliation was a New Jersey police detective who was demoted after his supervisor saw him put a campaign sign into his car to bring home. The sign happened to be for a politician whom the supervisor didn't like, and so the detective faced a demotion for this perceived political expression.
It will be helpful to know that, in this story, the campaign sign that the detective was carrying to his car wasn't for him, it was going to his mother. The detective in the case wasn't campaigning for the politician so disliked by his boss.
The lawsuit had been unsuccessful up to this point because the lower courts ruled that since the campaign sign didn't represent the detective's own beliefs, then he wasn't protected.
The above article quotes Justice Stephen Breyer in saying "The Constitution prohibits a government employer from discharging or demoting an employee because the employee supports a particular political candidate.” In this decision the court expanded this protection to include perceived political speech.
Breyer goes on to say that it's "the employer's motive" that counts.
The case, Heffernan vs. City of Paterson, found its way to the Supreme Court with the help of UCLA law professors Stuart Banner and Eugene Volokh who helped write the appeal to the circuit court's decision.