"Every practice and every game Mr. Elliott misses will hurt our team's chances of having a successful season and making to the 2017-18 NFL Playoffs and hopefully the Super Bowl". She testified at the appeal hearing this week that she believed Thompson's version of events was not credible.
"T$3 he NFLPA and Elliott do not seek in this Petition for the Court to make its own determinations about Elliott's or [the accuser's] credibility, or any other matter of fact-finding properly left to the arbitrator", the lawsuit reads, via Pro Football Talk.
"The idea that this was a conspiracy is false", league spokesman Joe Lockhart said.
Henderson is expected to rule on Elliott's appeal soon, according to The Associated Press. The NFL season kicks off Thursday night, and the Cowboys make their regular-season debut on September 10 on "Sunday Night Football".
Elliott denied Thompson's allegations under oath in an appeal hearing that spanned three days.
Roberts' conclusions were not included in the league's final investigative report of the incident, nor was she invited to a meeting with the four outside advisors selected by the commissioner to help him determine Elliott's punishment.
Why file the lawsuit now?
McCarthy said the league was "very confident" in its investigation. One witness claimed Thompson had encouraged her to lie to police about the alleged assault, and revealed text messages that supported that assertion.
The union will attempt to persuade a court to agree that Goodell's suspension of Elliott can't stand, even if Henderson backs it.
Henderson has heard dozens of appeals, including New Orleans running back Adrian Peterson's in a child abuse case out of Texas when Peterson was with Minnesota.
According to CBS Sports, Jeffrey Kessler, a lawyer representing Elliot, made a "claim that the "Elliott Report" (the document produced after nearly a year of investigatory work) "deliberately omitted a conclusion" as to what sort of punishment the league should hand down for Elliott".
It's unknown how long it will take Henderson to come to a decision, though there was a report on Thursday afternoon that he is being pressured to do so by Monday, and that the expectation is Elliott's suspension will be reduced.