A driver who said he unknowingly ingested methamphetamine before crashing his car has lost a claim dispute with his insurer.

The claimant was involved in a single-vehicle accident on September 29 2020, when his car left the road, flipped several times and hit a tree.

He said he was feeling unwell and experienced microsleeps before the crash, and had planned to pull over at a truck stop after a near-miss with another vehicle.

The Australian Financial Complaints Authority, in its dispute ruling, has acknowledged it was dark and rainy, and road conditions were poor at the time of the accident.

The complainant tested positive for methamphetamine in a blood sample taken about two or three hours after the incident. He was later charged with driving under the influence of drugs, to which he pleaded guilty, but he insisted his drink was spiked hours before the incident.

Allianz Australia declined his claim based on a policy exclusion around accidents involving a driver under the influence of drugs or who has been convicted of any related offence.

The insurer noted a report from a professor who concluded the driver had probably been experiencing “rebound fatigue from consuming methylamphetamine”. The report said the near miss before the crash would normally have awoken the man due to an “outpour of stress hormones”, rather than him falling asleep again.

The professor disputed the claim the man had been spiked, saying he would have shown fast and aggressive behaviours typically associated with peak methylamphetamine consumption. He suggested the man was probably “coming down” from a large dose of the drug taken at least 12 hours before the crash.

The complaints authority says Allianz showed it was entitled to decline the claim.

“The available information indicates the complainant suffered from rebound fatigue as a result of the drug consumption, which led to the accident,” the authority said. “The complainant accepts he was affected by the drug. The complainant’s account of microsleeps is in line with [the professor’s] description of rebound fatigue.”

The complainant said Allianz’s investigator told him there would have been “no objection” to the claim if he had not been convicted of the drug-driving charge.

But the investigator said the claimant initially denied taking drugs and that he advised the man to inform the insurer relating to the outcome of a court proceeding.

The authority says it is not persuaded that the insurer’s investigator told the man the claim would be accepted.

It says Allianz handled the claim appropriately and promptly responded to the claimant despite his delayed responses.

Click here for the ruling.