What you blow is what you go – New drink driving laws take effect

Police will no longer use a time consuming formula to calculate a drink driver’s blood alcohol content, under new laws to take effect from midnight on 11 September 2019.

Under the change, the roadside evidentiary reading will be the one used at their court appearance.

The new practice replaces a complicated back calculation procedure, where a person’s legal blood alcohol content is calculated according to the time of their last drink.

It allowed some drink drivers to manipulate the system with misinformation to escape higher penalties or avoid being charged at all.

The 1974 law meant police were using a time consuming formula in order to come up with a reading that would be the basis of any charge.

The move is part of the McGowan Government’s wider approach to making Western Australian roads safer and deterring unsafe driving behaviour.

Police and Road Safety Minister Michelle Roberts said, “It’s a sad reflection on the former government that WA is the last State in Australia to remove the back calculation practice.

“They failed to abolish this outdated practice, despite the evidence and recommendation to do so.

“It means what you blow is what you go. The reading you blow roadside will be the one used at your court appearance.

“It’s simple, it takes all the confusion away and it’s a clear message that alcohol and driving don’t mix.

“The safest thing to do if you’re drinking, is to make other plans to get home, said Minister Roberts. 

The removal of the blood alcohol content back calculation process from WA’s breath testing regime brings Western Australia in line with other Australian jurisdictions.