They saw him head down with both hands on the phone.
He was pulled over but could not produce his learner licence because he had lost it due to demerit points.
Asked why he was on his phone, he said he thought he could do so because he was stopped at the lights.
The 194 centimetre, 119 kilogram prop appeared in Ipswich Magistrates Court on Monday over the March 1 incident.
“Normally his de facto wife takes him to training,” his lawyer Campbell MacCullum told the court.
“She unfortunately couldn’t that day. He exhausted all avenues apart from, of course, calling a taxi.”
Haas, who played his fourth NRL game in the Broncos’ loss to the Wests Tigers on Thursday, did not comment outside court.
It was his first game of the season after serving a four-game ban and being fined $20,000 for failing to co-operate in an investigation relating to an incident involving his family.
The NRL integrity unit probe stemmed from two off-field incidents involving his family members, one a wild brawl at a local rugby league game late last year.
It was not alleged he was violent.
But his off-field actions feed into concerns over Anthony Seibold’s Broncos as they reel from a 2-4 start to the season to sit 13th on the ladder.
Haas showed promising signs in his start debut last week, making 164 metres and 42 tackles in 62 minutes.