A document obtained by ESPN.com showed Best's case against the league was dismissed from the Wayne County Circuit Court in Michigan on May 6 due to a nonservice dismissal without prejudice.
This likely means that Best, the plaintiff, did not serve the defendants in a defined period of time. This led to the case's dismissal. Best can refile the suit, but it is unclear if he will do so. His attorney in the case, Bret Schnitzer, did not return messages and an e-mail seeking comment Thursday.
Best spent last season at his alma mater, Cal, as a student assistant coach working with the Golden Bears' running backs. Best still holds school records for kick return average and the most 200-yard rushing games.
Schnitzer told ESPN.com in January, when the case was filed, that one of the purposes of the suit was to set up a medical fund for Best "in order to deal with future medical conditions out of this concussion syndrome."
Best had multiple concussions in the NFL with the Lions and had two concussions at Cal before entering the NFL. Part of Schnitzer's contention in January was that after the league knew about Best's concussion history in college, it still allowed him to be drafted.
Best was the No. 30 pick in the 2010 NFL draft. He played 22 games for the Lions, gaining 945 yards rushing and 774 yards receiving. He had 12 total offensive touchdowns in his career.
Best's concussions came as the league was adjusting its concussion policies and the treatment of concussions in the NFL.
"One of the goals of the litigation is to protect Mr. Best down the road in terms of his medical condition," Schnitzer said in January. "And problems that he may have in the future."
The Lions were not listed in the suit, but Best had filed a workers' compensation claim against the club.