Jennifer Margaret Ryrie downed two glasses of champagne on Melbourne Cup day last year before she got into the car with her 18-year-old daughter, who was still practising to gain her provisional licence, the court heard yesterday.

Sentencing the 51-year-old over the incident, Magistrate Robert Walker said Ryrie had engaged in "foolish and criminal" conduct by supervising an inexperienced driver when she was affected by alcohol.

Ryrie was heading along Northcliffe Drive near Kembla Grange on November 6 last year when her daughter was pulled over by police for a roadside breath test.

Police noticed Ryrie's breath smelt of alcohol and she quickly admitted to drinking two glasses of champagne earlier in the day.

She blew a positive reading and was arrested, later recording a 0.075 reading at the police station.

Ryrie pleaded guilty yesterday to low range drink-driving while sitting next to a learner.

Defence solicitor Anthony Williamson told the court Ryrie had a good driving record and had simply made a mistake.

He said Ryrie had downed one drink at an after-work Melbourne Cup function and had then gone home.

Not intending to drive for the rest of the evening, Ryrie had consumed another drink but soon learned she had to pick her son up and decided to supervise her daughter while she was driving.

Mr Williamson said his client had simply not thought about her responsibility as a supervising driver, as her daughter had nearly completed her mandatory driving hours and was competent behind the wheel.

The court was told Ryrie needed her licence for work and to care for her elderly mother.

Magistrate Walker did not record a conviction against her.