The former leader of Arizona’s highest court has been tapped to mediate bus labor talks getting underway January 4 in Phoenix.

Along with a federal mediator, former state Supreme Court Chief Justice Ruth McGregor will work with the city’s contracted bus service provider and union workers.

This latest dispute involves a company called Transdev. Union members voted to authorize a strike a couple months ago after rejecting Transdev’s final offer. The union has cited bereavement time, uniform allowances and pay as sticking points.

This marks the third time the city has hired McGregor. Earlier this year, Phoenix paid McGregor $6,000 for helping to reach a deal between employees with Amalgamated Transit Union and First Transit.