Convicted drink drivers in Western Australia who get their licence back will have to pay for a breath-test lock that stops them from driving under the influence.

The alcohol interlock will be installed for at least six months and cost the driver between $1600 and $2200 to hire.

A subsidy of $50 a month is available to people with concession cards.

If the driver provides a positive breath test, their vehicle won't start.

Those who are permanently disqualified from driving but are granted an extraordinary licence will be fitted with the device for three years.

Data from the device will also be monitored and people who show they cannot separate drinking and driving will be referred for compulsory alcohol assessment and treatment.

Attorney General Michael Mischin told state parliament on Tuesday that drink drivers were the authors of their misfortune and ought to bear the bulk of the cost to prevent them from offending again.

Alcohol was a factor in a quarter of fatal crashes and one in 10 serious injury crashes, Police Minister Liza Harvey said.

Ms Harvey said since 2008, the rate of fatalities in WA had dropped 23 per cent, but no road deaths should be accepted.

"This legislation will target those drink drivers who fail to get the message that their irresponsible actions kill," she said.