Safety Eric Reid, bottom right, has been one of the most outspoken NFL players on social justice issues. (Jeff Chiu/Associated Press)

Eric Reid appeared to be one of the most reliable defensive backs on this year’s NFL free agent market, at least on paper. But he’s still looking for a job, and his continued unemployment has prompted a second grievance filed against the NFL. The NFL Players Association filed a noninjury grievance related to Reid’s free agency Monday, the union said in a statement.

It marks the union’s most formal defense yet for players who have protested racial injustice and police brutality during the playing of the national anthem. The grievance is related to questions the safety has been asked about his plans to continue kneeling during the anthem next season.

“According to our information, a club appears to have based its decision not to sign a player based on the player’s statement that he would challenge the implementation of a club’s policy prohibiting demonstration, which is contrary to League policy,” the NFLPA said in a statement.

The grievance is connected to Reid’s only known free agency visit this offseason, when the Cincinnati Bengals reportedly asked him last month whether he intended to continue protesting, according to a person familiar with the filing. While the Bengals might have made clear that they expect all of their players to stand for the anthem, the union’s grievance says teams are operating outside of league rules, which do not require players to stand.

“We believe these questions are improper, given League policy,” the NFLPA said in its statement.

A spokesman for the Bengals declined to comment on the grievance.

In addition, the NFLPA filed a system arbitration case on behalf of all players, which aims to stop clubs from asking any player whether he intends to protest during the national anthem.

Reid had filed his own grievance Wednesday, charging owners with colluding to keep him out of the league. Reid has been among the most prominent players to protest by taking a knee during the national anthem. He’s said from the earliest days of free agency, which began in March, that teams won’t sign him because of his social activism, even though he’s said he’s willing to stand during the anthem next season.

Both grievances are now subject to a confidential arbitration process under terms of the collective bargaining agreement between NFL owners and the players’ union.

The NFLPA was not a formal party to Reid’s initial complaint, but has been supportive of the player’s decision, according to a person familiar with the situation, offering legal counsel and resources. “Our union supports Eric and we are considering other legal options to pursue,” a spokesman said in a statement last week.

Reid was the second player to charge the NFL owners with collusion over the anthem protests, and he’s using the same legal team as quarterback Colin Kaepernick, who remained unsigned all of last season.

“Colin and Eric have taken courageous action at the expense of their professional careers and personal lives,” their attorneys, Mark Geragos and Ben Meiselas, said in a statement Monday. “They did these selfless acts because they wanted to shine light on inequity and oppression. Today they welcome all NFL Players who have joined in the prosecution of the NFL for their conspiracy and illegal acts. We stand shoulder to shoulder with the NFLPA in our fight for justice, equality and inalienable rights of all Americans.”

Even without Kaepernick in the league, Reid continued the protests last year, repeatedly explaining that his protest targeted “systemic oppression.”

Reid, 26, was a first-round draft pick by the San Francisco 49ers in 2013, made the Pro Bowl that year and has tallied 10 career interceptions in five seasons.

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