Simpson confirmed Tuesday that he was absent from practice Monday to attend a hearing on his case at league headquarters in New York. Simpson told reporters he "just told them the truth" and that "the records and the facts show what happened."
He acknowledged, however, he was unsure whether his argument would persuade the NFL to reduce or eliminate any punishment.
"I'm not a decision-maker with that, so I really can't put a fact on that or point to it," Simpson said.
Simpson was arrested last November on suspicion of drunken driving when his sports car broke down on a freeway just outside of downtown Minneapolis. According to the Minnesota State Patrol, a trooper observed him with watery eyes and slightly slurred speech, but Simpson denied he'd been drinking.
In January, Simpson pleaded guilty to careless driving and refusing to submit to a chemical test, avoiding jail time and the DUI charge. He was ordered community service and two years of probation.
David Valentini, Simpson's defense attorney, accompanied him to the league office.
"It went great. My lawyer said I did great," Simpson said.
Simpson served a three-game suspension to start the 2012 season, stemming from a felony drug conviction for a marijuana shipment authorities found at his home in Kentucky while he played for Cincinnati.
"Until I hear differently, I expect him to be here," coach Mike Zimmer said.
Offensive coordinator Norv Turner dismissed any concern about losing Simpson, the team's best deep threat, in September.
"I just have a different take on those things. You have to have a varied plan. Unfortunately, in this game, guys miss," Turner said. "If it's a case where someone misses because of an off-the-field thing, that's one thing.
"We could be in the opening game and someone we are counting on to play a big role sprained his ankle on the third play. We have to have a plan to go play and do the things we want to do. So, yeah, we have plans and there are certain plays that Simpson is really good on. There are other guys that have to fill in, if he's not in for that play."