The suit, filed Monday in federal court in New York, asks for the court to throw out arbitrator Fredric Horowitz's decision to suspend Rodriguez for the 2014 season and postseason. The lawsuit claims that the players' union "completely abdicated its responsibility to Mr. Rodriguez to protect his rights," allowing Major League Baseball to take advantage of his confidentiality rights. It alleges the union failed to protect Rodriguez and that MLB violated agreements it had with the union.
Rodriguez and his legal team also made Horowitz's 33-page decision public. The decision to shorten Rodriguez's suspension to 162 games from its original 211 games was made by a three-member panel chaired by Horowitz and representatives from MLB and the players' union.
In his decision, Horowitz wrote there is "clear and convincing evidence" that Rodriguez used three banned substances and that he tried to interfere with MLB's drug investigation on two occasions.
"While this length of suspension may be unprecedented for a MLB player, so is the misconduct he committed," Horowitz wrote.
Rodriguez, who admitted taking steroids earlier in his career while playing for the
Horowitz concluded in his decision that Rodriguez used testosterone, human growth hormone and insulin-like growth factor-1 in violation of baseball's drug policy.
"A suspension of one season satisfies the structures of just cause as commensurate with the severity of his violations," Horowitz wrote.
The Associated Press contributed to this post.