If Tom Brady’s suspension is upheld, the quarterback plans to mount a legal challenge. (Lucy Nicholson/Reuters)

Tom Brady and the NFL Players Association plan to challenge the NFL in federal court if the New England Patriots quarterback receives a suspension of any length once Commissioner Roger Goodell decides on Brady’s appeal, a person familiar with the situation said. ABC News first reported Brady’s plan.

Brady, the person said, could still change his mind. But barring a change of heart by Brady once Goodell announces his ruling, which is expected soon, the legal fight between the league’s embattled commissioner and its tarnished Super Bowl MVP could move from the league offices to a federal courtroom.

In May, the NFL suspended Brady four games for his alleged role in deflating footballs before the AFC Championship Game in January. Brady appealed the ruling days later. Goodell appointed himself to hear the appeal, to the protestation of the NFLPA and Brady’s camp.

“If they get to federal court, the whole procedure, the question is whether it was arbitrary and capricious,” said Alan Milstein, the lawyer who represented Maurice Clarett in his fight against the NFL. “It seems fairly clear it was.

“The commissioner,  I thought, really made a poor choice in taking part – basically trying to become part of this arbitration. The best argument Brady has is that due process was lacking and the hearing was unfair. The best evidence is that the commissioner was part of this thing.”

[Brady likely to sue if suspension upheld]

If Brady gets suspended and sues, the NFLPA would file its challenge in either a Minnesota or Massachusetts court, the person said. Minnesota is perceived as a pro-labor court system, and a hearing in Massachusetts would serve as a home game of sorts for Brady.

Any appeal in federal court would include a request for an injunction to delay any suspension until a decision is reached. Essentially, Brady and the NFLPA would ask that the court freeze the ban until the case ends. The bar to attain an injunction is low – lawyers would only need to show that Brady had been caused “irreparable harm” by the NFL’s decision.

The timetable for a potential court case is unpredictable. And so if the court grants an injunction and the case either drags or is scheduled for late in the fall, it’s possible Brady could begin the season behind center regardless of Goodell’s decree or the eventual outcome of the federal court case.

The timetable, then, could also affect Brady’s strategy if it drags: Would he and the Patriots prefer to know his status, one way or the other, before training camp? Before Week 1? If Goodell reduces his suspension to just one game, would he rather skip the opener than enter the season with his status uncertain?

[Jenkins: Goodell has only one good option in Deflategate mess]

If the NFL suspends him, one rationale for Brady taking the case to federal court would be simple: At that point, he would have nothing to lose. The bar for a federal court to reverse a private arbitration result is notoriously high. But the NFLPA believes it has a strong argument, already being prepared, based primarily on five points, which an NLFPA source laid out.

• The NFL policy for handling equipment in the NFL is in the club manual and pertains to club personnel, not players. The NFLPA would argue that the NFL suspended Brady four games under a policy that doesn’t apply to him.

“That’s an excellent argument,” Milstein said.

• The Wells Report, the investigation on which the NFL based its suspension, alleged Brady was “at least generally aware” that footballs had been tampered. The NFLPA would argue that the “general awareness” standard has no legal merit – either Wells found direct evidence, or he didn’t.

• The NFLPA would argue Brady – given the rules in the club manual did apply to him – received a punishment without precedence. Under the collective bargaining agreement, players have a right to know specific punishment for specific violations.

• The NFLPA plans to cite a specific example in oral arguments in an effort to prove Brady’s suspension was arbitrary. Last year, the league caught the Minnesota Vikings tampering with footballs by placing them in a dryer, a violation of the club manual. The team, the NFLPA source said, received a letter from the league and no further reprimand.

• The NFLPA would mount an argument against the procedure the Wells Report used to measure the inflation and deflation of footballs, saying there was no previous standard.

Because of how federal courts view arbitration hearings and rulings made in private venues, such as sports leagues, Brady’s best chance at winning a potential challenge in court might be the NFLPA’s assertion Goodell himself was unfit to serve as the arbiter of Brady’s appeal. The NFL announced that Executive Vice President Troy Vincent made the initial ruling against Brady. Goodell insisted he could arbitrate independently of Vincent’s decision. The NFL will argue that Goodell had input in the initial decision and was therefore a biased arbiter.

“Definitely start with that,” Milstein said. “Everybody knew he should have bowed out. For the life of me, I can’t figure out why – it was like a public decision he made, he’s going to be judge and jury.”

Federal courts rarely reverse rulings, even if they find fault with how arbitrators arrived at the ruling. But the reversals almost always come because the court sees an issue with the arbitration process itself. And so, if the NFLPA can prove that Goodell judged Brady’s appeal with bias, the suit could win.

The NFLPA beat the NFL in a similar instance last February, when Judge David Doty overturned the NFL’s suspension of running back Adrian Peterson.

Brady has also retained lawyer Jeffrey Kessler, who successfully fought the NFL on legal grounds during the New Orleans Saints’ Bountygate scandal in 2008.