From a recent article on

Coles dismissed the driver after a December 1 oral swap produced an unconfirmed methamphetamine reading.
A second test provided a positive test for cannabinoids but not for methamphetamine.

He said “the first one came up for methamphetamine and then when they’ve done. . . re-tested me 30 seconds
later and sent that back and there’s no meth and then all of a sudden it’s, yes, THC’.

Read the full article here: COLES Driver Sacked – Oral Test