A winery tour with colleagues that became a drunken and aggressive "day from hell" for a Victorian policeman has had a sobering conclusion in a Melbourne courtroom.

A magistrate who heard how drunk Jonathan Moss had got described the former senior constable as "blotto" and "as full as a state school".

The magistrate Tim Walsh was told that Moss started drinking chardonnay and shiraz at 9am on September 11 last year, and more than eight hours later returned to a suburban police station.

Prosecutor Temple Saville said that Moss later assaulted an acting sergeant in a car after the colleague agreed to drive him home.

Ms Saville told Melbourne Magistrates Court on Friday that Moss, then performing temporary duties with the Brimbank crime investigation unit and a member for four years, insulted, threatened and injured acting Sergeant Matthew Moohan.