The new laws that came into affect on Monday are aimed at repeat offenders.

Offenders will face harsher jail terms, a three-month licence disqualification for a first court conviction, drug dependency assessment and lowering the minimum age of people who attend or are admitted to hospital for treatment as a result of marine vessel or motor vehicle accident.

Whyalla Police Station Senior Sergeant Steve Sims said any rule or regulation to make the roads safer was welcome.

He said it was important to reduce the number of drunk drivers on the roads.

Road safety minister Michael O'Brien said the laws are part of a package of reforms, including the Mandatory Interlock Scheme, which this year is anticipated to prevent up to 2700 drink driving offenders from starting their vehicles if they register a positive blood alcohol reading.

"The statistics show 23 per cent of drivers or riders killed on our roads between 2005 and 2009 tested positive to drugs," Mr O'Brien said.

"The percentage of road users killed while driving with a blood alcohol level over 0.05 has increased significantly over the last decade from a low of 25 per cent in 2000 to an average of 37 per cent in the five year period (2005-2009)."

Further statistics revealed that on average over the same five year period, 73 per cent of all driver and rider fatalities with a blood alcohol reading above 0.05 were, over 0.15.