ALBANY — The state's highest court on Tuesday unanimously upheld an order requiring the reinstatement of a Shenendehowa bus driver who was fired after she failed a random drug test for marijuana.

The Court of Appeals ruling supported the conclusion of an arbitrator who determined the firing of Cynthia DiDomenicantonio on Nov. 10, 2009, was too severe a punishment for the district employee of 10 years.

The school district, represented by attorney Beth Bourassa, had argued that it had adopted a zero-tolerance policy for positive drug tests. The bus driver's attorney, Daren Rylewicz, countered that such a policy did not exist.

The arbitrator — who became involved after the bus drivers union, the Civil Service Employees Association, challenged the firing — found the dismissal violated the collective bargaining agreement.

The arbitrator ordered DiDomenicantonio reinstated — minus six months of back pay, follow-up drug testing and substance-abuse counseling.

A state Supreme Court justice reversed the arbitrator's ruling. That decision was, in turn, reversed by the Appellate Division of state Supreme Court, setting the stage for Tuesday's final decision by the Court of Appeals.

The Court of Appeals said there are three narrow grounds in which an arbitrator's conclusion can be vacated: if it violates public policy, is irrational, or clearly exceeds a specifically enumerated limitation on an arbitrator's power.

"None of these grounds has been established here," the high court ruled.

"The arbitrator's decision did not exceed a specific limitation on his power; nor was it irrational. Rather, he determined that, contrary to the school district's argument, the parties' agreement did not require the penalty of termination in these circumstances and that the district did not in fact have a zero tolerance policy. The consequent determination that reinstatement with conditions was the appropriate penalty did not violate public policy."

The decision was handed down by Chief Judge Jonathan Lippman and Associate Judges Victoria Graffeo, Robert Smith, Susan Read and Eugene Pigott.

The ruling was 5-0 because the court was missing two judges following the retirement of Senior Associate Judge Carmen Beauchamp Ciparick and the death of Associate Judge Theodore Jones. Ciparick's successor, Associate Judge Jenny Rivera, was confirmed by the state Senate on Monday but had no input on the ruling.

rgavin@timesunion.com • 518-434-2403 • @RobertGavinTU