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What you blow is what you go laws explained

New laws around calculating blood alcohol content are set to take effect from midnight.

Police will no longer use a time consuming formula to calculate a drink driver’s blood alcohol content, under the new Blood Alcohol Content Bill 2019. Instead drink drivers will be charged based on what they blow roadside.

The new practice of using the “evidentiary” reading 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.

This brings Western Australia in line with other Australian jurisdictions.

Senior Sergeant Simon Baxter explained the new laws to Oly and Perth LIVE listeners.

  • The BAC limit is STILL 0.05
  • The first breath test is the PRELIMINARY test.
  • If the driver records a reading over 0.05, they will be required to complete a second EVIDENTIARY test 15 minutes later
  • The reading on this SECOND test is the one used to fine and/or charge the driver.
  • There will no longer be a back calculation completed based on the driver’s last drink.

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