Shelley Cooper, 45, of Gay Street, Warrnambool, pleaded guilty in the Warrnambool Magistrates Court to refusing to accompany a police officer for an evidentiary drug test.

It was the second time Cooper had been found guilty of that offence and magistrate Mark Stratmann said there was a mandatory minimum licence ban that had to be imposed - four years.

Cooper was obviously stunned by the licence disqualification and said she thought the ban would be for just 12 months.

She had said she was not currently working and wanted to go back to school after she got her licence back.

Mr Stratmann said he would not go beyond the mandatory minimum term but that was what had to be imposed.

He also convicted and fined Cooper $1200 with $82.40 costs.

Police alleged that at 7pm on November 13 last year offices pulled over Cooper driving a black Ford Falcon in Warrnambool's Wanstead Street.

She had a current licence and a preliminary breath test for alcohol indicated Cooper was under the legal limit.

But, she returned a positive to a preliminary oral fluid drug test before refusing to accompany police to the Warrnambool police station for an evidentiary drug test.

Cooper's prior for the same offence was in 2016.

She told police she just wanted to go home, had one joint of marijuana the day before and it had been a horrible day which included her being pressured to drive.

In court she told the magistrate she had been stubborn by not going with the police officer but was now using alternate treatment methods for her arthritis.

"I have to take responsibility for my actions," she said.

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