ILLICIT drug users who drive are running a much greater risk of being caught by police than drink-drivers.

That is because recreational drugs such as cannabis and methamphetamine (ice) can be detected in a person's bloodstream days after the substance is used, whereas alcohol is cleared out of the system within hours, depending on the amount drunk.

Even drivers apparently unaffected by drugs they consumed days ago are being charged.

The growing number of drivers caught out is being reflected in Wagga Local Court's criminal list every Wednesday.

Three weeks ago, the number of people appearing in court charged with driving with an illicit drug in their blood was six, compared to five drink-drivers.

This Wednesday, 13 alleged drug-drivers were on the list and just one alleged drink-driver.

The recent shift in balance between the two offences was noted by magistrate Michael Antrum.

"What I have noticed sitting on the bench here over the past couple of months is Wagga police are very active in testing for amphetamine and cannabis in the system," Mr Antrum said.

"If people are using it (an illicit drug) they are going to get caught."

Mr Antrum said drugs such as ice and cannabis had a different physiological action in the body than alcohol.

He said people understood to some degree how long it took for alcohol to leave their system, but drugs took a much longer time.

One man fined $330 and disqualified from driving for three months after pleading guilty to driving with cannabis in his system admitted he did not know drugs could be detected so long after they were used.

"I just tried it a couple of times with my mates," he said.

He said he had not touched cannabis since being charged.

Another man - a truck driver - lost his job after his boss saw he had been charged with driving with ice and cannabis in his system.

The man pleaded guilty to cannabis, but said there had been a testing error that led to a wrong indication of ice.

"My boss saw the positive result and that was the end of it," the man said.

"I do it (use cannabis) on the weekends occasionally, I don't do it during the week."

The man was fined $440 and disqualified from driving for three months.

"You need to find another way to relax, try yoga," Mr Antrum suggested.

A number of other cases were adjourned to later dates or other courts for sentence after guilty pleas were lodged by their solicitors, while some people were dealt with in their absence after failing to front court.

One man pleaded guilty but on the basis he had cannabis only in his system.

He will dispute police facts that allege he tested positive also to amphetamine.

Police now regularly test drivers for drugs.

During one blitz in the Riverina in June, 48 out of 600 drivers tested - or nearly one in 12 - tested positive for cannabis or ice.