Nobody doubts Peter Marshall's commitment to the United Firefighters Union and his members. But there is real and growing doubt, even among those close to him, about the firebrand union leader's political judgment.

Negotiations between fire chiefs and the UFU aimed at updating the enterprise bargaining agreement from 2010 have been dragging on for more than two years, with progress stalled for months.

Now, the union's extraordinary bid to injunct the Metropolitan Fire Brigade's new pro-diversity selection procedure, and the MFB and Country Fire Authority seeking to force the introduction of part-time firefighters are further evidence that both sides have given up on talks and compromise.