Dallas Cowboys running back Ezekiel Elliott has been suspended for the first six games of the 2017 season. (Gus Ruelas/AP)

Ezekiel Elliott, the standout second-year running back for the Dallas Cowboys, has become the latest NFL player to challenge a disciplinary measure taken against him by the league. Like those before him, Elliott faces long odds in attempting to have his penalty reduced or overturned, given the structure of the sport’s system of player discipline.

Under the sport’s rules, Elliott’s appeal could have been heard and decided by Commissioner Roger Goodell or a person designated by him. On Wednesday, the league confirmed that former NFL labor relations executive Harold Henderson will handle the appeal at an Aug. 29 hearing. The Cowboys play their final preseason game on Aug. 31.

“The default answer has always been that the player has an uphill battle on appeal,” Gabriel Feldman, the director of the sports law program at Tulane, said in an interview before the NFL announced Henderson’s appointment. “The first question is: Who’s going to hear the appeal? If it’s the commissioner, it’s an even more uphill battle. Roger Goodell has had a chance to consider the evidence. The issue is whether Elliott and his legal team can present new evidence or mitigating factors.”

The NFL announced Friday that it had suspended Elliott, the NFL’s leading rusher last season as a rookie, for six games without pay under the sport’s personal conduct policy, citing a pair of incidents involving women. The NFL Players Association announced Tuesday that it would appeal Elliott’s penalty on his behalf.

“We will represent Ezekiel, as we do all players, to ensure that the NFL is held to its obligation of adhering to principles of industrial due process under the collective bargaining agreement,” the NFLPA said in a written statement.

Elliott, his legal representatives and the NFLPA could choose to go to court if they are dissatisfied with the outcome of the appeal. But their chances of overturning Elliott’s suspension could be even slimmer there, given that Goodell’s authority in player-disciplinary matters was recently reinforced by the long but ultimately unsuccessful legal challenge of the four-game suspension given to New England Patriots quarterback Tom Brady in the infamous Deflategate case.

“This is the opportunity for Elliott and his legal team to present new evidence, mitigating factors,” Feldman said in a phone interview. “This is the last chance for that. Once the appeal is considered and resolved, that’s when it becomes nearly impossible to overcome the commissioner’s authority to resolve these issues. If it goes to court, you’re talking about different policies, a different case, a different set of circumstances. But it’s the same broad deference given to an arbitrator’s decision.”

The NFL investigated Elliott’s case and gave him the baseline suspension for a domestic violence offense under the revised personal conduct policy enacted by the league in December 2014. That policy calls for a six-game suspension without pay for a first offense, subject to the possibility of being increased or decreased based on circumstances.

Goodell determined the length of Elliott’s suspension, according to the league, with input from a panel of four outside advisers. Goodell did not participate in a meeting between Elliott, Elliott’s representatives and NFL officials in June. That meeting was overseen, according to a person familiar with the investigation, by B. Todd Jones, the NFL’s chief disciplinary officer.

The league cited incidents last year involving Elliott and his former girlfriend, who accused him of domestic violence. Elliott was not charged with a crime by authorities in Columbus, Ohio. The NFL also mentioned an incident this year in which Elliott is said to have pulled down a woman’s shirt at a St. Patrick’s Day Parade in Dallas.

In Elliott’s appeal, his legal team reportedly plans to raise issues about the credibility of Elliott’s accuser in the Columbus case, saying that she threatened to ruin his career. Elliott’s representatives have called the findings of the NFL’s investigation “replete with factual inaccuracies and erroneous conclusions” and have said the league “cherry picks” the evidence on which it chooses to focus.

“There’s the possibility the suspension could be reduced,” Feldman said. “But there was a lengthy investigation by the NFL. The standard in the personal conduct policy is pretty low. It just requires credible evidence. Based on his first review, Roger Goodell determined there was credible evidence.”

The NFLPA has challenged previous penalties in recent years, with mixed success.

It challenged the penalties given in 2014 to Ray Rice, Adrian Peterson and Greg Hardy under the personal conduct policy.

Goodell chose Barbara S. Jones, a former federal judge, to resolve Rice’s appeal, and she overturned Rice’s indefinite suspension by ruling that Goodell overstepped his authority by punishing Rice a second time after originally suspending him for only two games. Rice has not been signed by a team, however, despite his attempts to return to the NFL.

Henderson, who will hear Elliott’s appeal, was chosen by Goodell to hear Hardy’s appeal and reduced Hardy’s suspension from 10 to four games. Henderson upheld Peterson’s suspension. That sent the union and Peterson to federal court. They prevailed in front of U.S. District Judge David S. Doty, who sent the case back to the NFL for further proceedings under the collective bargaining agreement, but Doty’s decision was overturned on appeal.

Brady and the union likewise prevailed at the district court level, putting Brady’s four-game suspension on hold and permitting him to play the entire 2015 season, but lost on appeal, resulting in Brady missing the first four games of last season.

“We hold that the Commissioner properly exercised his broad discretion under the collective bargaining agreement and that his procedural rulings were properly grounded in that agreement and did not deprive Brady of fundamental fairness,” the appeals court wrote in its decision reinstating Brady’s suspension.

The union has been adamant about its desire to reduce Goodell’s power in matters of player discipline, seeking to have appeals heard and resolved by an independent arbitrator. The matter is likely to be addressed in the next set of CBA negotiations between the league and union after their bid to reach a separate deal on the issue unraveled. In the meantime, Elliott and other players disciplined by the league must deal with the system as currently constructed.

“This is his last chance and his best chance to make an argument based on the facts of the case and the strength of the evidence considered,” Feldman said. “Once the appeal is finished, if it were to go to court, a judge generally is not going to reconsider the facts of the case.”

More NFL coverage:

While Jay Cutler and Adam Gase reunite in Miami, Colin Kaepernick keeps waiting

Ezekiel Elliott suspension: An inside look at the NFL’s investigation and punishment decision

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