It was hardly a surprise that lawyers for Alex Rodriguez went to federal court in Manhattan yesterday to try to halt his season-long doping suspension. What was intriguing was the degree to which the legal filing they made to overturn the suspension targets Rodriguez's union, contending that it "abdicated its responsibility" to defend the Yankees' third baseman as baseball moved to suspend him.

The filing, as expected, also singles out Major League Baseball and accuses Fredric Horowitz, the arbitrator who ruled on Saturday that Rodriguez should sit out all of the 2014 season, of a "manifest disregard for the law" in arriving at his decision.

It says that Horowitz, who did reduce the original 211-game ban that baseball imposed on Rodriguez in August to a full season of 162 games, did not display impartiality as an arbitrator and refused to consider evidence that Rodriguez’s side presented in its efforts to have much, or all, of the suspension overturned.

But it was the strategy to go after the players association - described by legal experts as a necessary step for Rodriguez to build his case that he was not adequately represented - that stood out and underlined just how many opponents Rodriguez has now accumulated in seeking to remain on the field.

Among other things, the filing accuses the union of failing to intervene to stop the leaking of “prejudicial information” by Major League Baseball and of failing to stop what it described as the “abusive investigative tactics” that baseball used to obtain evidence against Rodriguez. In addition, the filing says the union provided only perfunctory help during Rodriguez’s actual arbitration hearing.

Three pages also single out statements made by Michael Weiner, who died last November of brain cancer after four years as head of the players union. Weiner was popular among his constituents, and Rodriguez even attended his funeral.

Still, the filing is directly critical of Weiner, contending that several statements he made last summer - most notably, his comment, in a radio interview, that he had advised Rodriguez to accept a suspension if the number of games was at a certain number - had the effect of prejudging Rodriguez’s guilt and “corrupted the arbitration process.”

Early yesterday evening, the players association responded to the filing's harsh words with a toughly worded two-paragraph statement. In it, the new head of the union, Tony Clark, said the claim by Rodriguez's lawyers that it had failed to adequately represent Rodriguez was "outrageous." And he described the criticism of Weiner as "gratuitous" and "inexcusable."

Remarkably, the union had risen to Rodriguez’s defence just 24 hours before, accusing baseball officials on Sunday night of “piling on” by participating in a piece on the Rodriguez case that ran on CBS’s 60 Minutes.

But that was Sunday. On Monday, the dynamics changed as Rodriguez’s lawyers appeared in front of Judge William H Pauley III in advance of their filing so they could argue that portions of it be kept confidential.

Pauley, according to a transcript provided by Rodriguez's representatives, denied the request, noting that baseball's commissioner, Bud Selig, had appeared on 60 Minutes to discuss the case Sunday evening.

“Given the intense public interest in this matter and commissioner Selig’s disclosures last night on 60 Minutes, it’s difficult to imagine that any portion of this proceeding should be under seal,” Pauley said, according to the transcript.

As a result, Horowitz’s written decision, which had remained confidential through the weekend, was released, providing some insight into his rationale for issuing the season-long ban. In his decision, Horowitz wrote that the evidence showed that Rodriguez committed three distinct violations of the doping rules.

He said testimony he heard from Anthony Bosch, who ran the South Florida anti-aging clinic at the centre of the Rodriguez case, was "direct, credible and squarely corroborated by excerpts from several of the hundreds of pages of his personal composition notebooks."

Horowitz also said there was reason to believe that Rodriguez had interfered with baseball’s investigation of the clinic. “Based on the entire record from the arbitration, MLB has demonstrated with clear and convincing evidence there is just cause to suspend Rodriguez for the 2014 season and 2014 postseason for having violated the JDA by the use and/or possession of testosterone, IGF-1, and hGH over the course of three years, and for the two attempts to obstruct MLB’s investigation,” Horowitz wrote.

JDA refers to the joint drug agreement between Major League Baseball and the union, a pact that spells out testing protocols and penalties. New York Times Service