From BR Bullpen

An Arbitrator is a quasi-judicial official who is hired to make a binding decision in a dispute between two parties. Recourse to an arbitrator is considerably less costly and quicker than seeking a resolution of the dispute through the court system, which is why it is a common feature of labor relations.

In Major League Baseball, the position of arbitrator dates back to the Collective Bargaining Agreement resulting from the 1972 strike, which introduced salary arbitration. An arbitrator was hired to rule on salary disputes between players and owners, as well as on grievances stemming from the CBA. Salary arbitration still constitutes the bulk of an arbitrator's work, although ruling on disciplinary matters, drug testing and other contract-related grievances also forms part of the workload.

MLB's first arbitrator was Peter Seitz. He was fired by the owners after making his momentous decision to discard the reserve clause and grant free agency to pitchers Andy Messersmith and Dave McNally following the 1975 season. Among others who have held the position, which is jointly funded by MLB and the Major League Baseball Players Association, are Raymond Goetz, Richard Bloch, who shortened the penalties imposed to five players accused of consuming cocaine in the early 1980s, and Thomas Roberts and George Nicolau, who ruled that the owners were practicing collusion later that decade. From 1999 to 2012, the position was held by Shyam Das. He was succeeded by Fredric Horowitz from 2012 until November of 2016, by Mark Irvings in June of 2017 and by Martin Scheinman at some point in 2021.