MLB informed Das and the players' association of its decision last week. Das had been baseball's permanent arbitrator since 1999, part of what technically is a three-man panel that also includes a representative of management and labour.
"Shyam is the longest-tenured panel chair in our bargaining relationship," union head Michael Weiner said. "For 13 years, from the beginning to the end of his tenure, he served the parties with professionalism and distinction."
Baseball's collective bargaining agreement says the arbitrator can be removed by the players' association or management at any time with written notice.
"I had the distinct privilege to serve as chair of the MLB-MLBPA arbitration panel for almost 13 years," Das wrote in an email to The Associated Press. "I have the greatest respect for the representatives of both parties I worked with during that period, and I wish the parties well in their ongoing relationship."
MLB executive vice-president Rob Manfred declined comment, spokesman Pat Courtney said.
The sides will now try to select a successor. If they cannot agree, baseball's collective bargaining agreement calls for them to ask the American Arbitration Association for a list of "prominent, professional arbitrators." The sides would then alternate striking names from the list until one remains.
One of the first cases the new arbitrator could hear is a grievance over a 100-game suspension issued last week to San Francisco reliever Guillermo Mota. The pitcher's agent, Adam Katz, said the positive test was caused by a banned substance contained in children's cough medicine.
Das, a graduate of Harvard and Yale University Law School, also has been an arbitrator for the NFL since 2004 and is scheduled to hear a grievance in the New Orleans Saints bounty case on Wednesday.
The baseball situation, "does not impact his role at an arbitrator for our CBA," NFL spokesman Greg Aiello said.
Following a grievance hearing, Das decided in February to overturn the 50-game suspension of Braun for a positive drug test. Lawyers for the Milwaukee outfielder, the reigning NL MVP, argued that the collection procedures specified in baseball's drug agreement for the urine sample were not followed with Braun's sample last Oct. 1 because it was not immediately left at a Federal Express office.
The collector testified that because the sample was taken on a Saturday and could not have been shipped that day to the testing laboratory outside Montreal, he concluded the sample would be more secure at his home. He then took it to a FedEx office on the following Monday.
Baseball's drug agreement states that "absent unusual circumstances, the specimens should be sent by FedEx to the laboratory on the same day they are collected."
Management loudly and publicly disagreed with his decision.
The sides asked Das to hold off on issuing a written decision while they negotiated changes to the drug agreement.
The 100-game suspension of Colorado Rockies catcher Eliezer Alfonzo for a second positive test, announced last Sept. 14, was rescinded in an agreement between management and the union on Monday.
"Alfonzo's grievance challenging his suspension raised issues that were nearly identical to those resolved in the arbitration involving Ryan Braun," MLB said in a statement. "It is not anticipated that any other future cases will be impacted by the circumstances raised in the grievances of these two players."
Under baseball's drug agreement, grievances are heard before initial suspensions are announced. In the case of penalties for a second or third positive test, the cases are argued after the suspensions are made public.
Alfonzo was designated for assignment by the Rockies on May 7 and sent outright to Triple-A Colorado Springs in the Pacific Coast League two days later.
Das took over as baseball's permanent arbitrator from Cornell professor Dana Eischen, who was hired in December 1997 but quit after ruling the following May against J.D. Drew's grievance seeking free agency.
Many of baseball's grievance arbitrators have had brief tenures, with the list including Lewis Gill (1970-72), Gabriel Alexander (1972-74), Peter Seitz (1974-75), Alexander Porter (1977-79), Raymond Goetz (1979-83), Richard Bloch (1983-85), Thomas Roberts (1985-86), George Nicolau (1986-95), Nicholas Zumas (1995-97) and Eischen (1997-98).
Joseph Sickles heard one case in 1976, and temporary arbitrators were used between Eischen and Das.
Seitz was fired after he ruled against owners in the Andy Messersmith-Dave McNally reserve clause case that led to free agency. Roberts was fired after deciding management colluded against free agents between the 1985 and 1986 seasons.
AP Pro Football Writer Barry Wilner and AP Sports Writer Mike Fitzpatrick contributed to this report.