Following a grievance hearing, arbitrator Raymond Goetz lifted suspension two weeks later.
"As a practical matter, the commissioner was compelling Jenkins to jeopardize his defense in court. While this may not actually violate any principles of constitutional or criminal law, it offends the moral values of our society on which the legal privilege against self-incrimination is based," Goetz wrote.
He said players should not be required to prove their innocence because "this approach would stand the requirement of just cause for discipline on its head."
In the Biogenesis case, an arbitrator would have to rule whether refusing to answer questions while no criminal charges are pending may be penalized under the "just cause" provision of the drug agreement.
Horowitz, a veteran of baseball and NHL salary arbitration cases, was appointed baseball's arbitrator in June last year. Shyam Das, who had served since 1999, was fired in May 2012, three months after overturning a 50-game suspension imposed on Braun. Das ruled the urine sample of the Milwaukee star was not handled by the drug collector in the manner specified by baseball's drug agreement.