Evidential tests were carried out at police stations or in a drink driving bus, and took an hour or more to carry out. However, roadside screening tests could be done in 15 minutes or less.
"I think that we could actually lower the evidential standard and actually rely on the roadside breath screening test for those lower levels," Mr Shadbolt said.
"We could balance that by giving the driver the option of asking for an evidential breath test if they doubt the readings of the roadside breath screening test.
"But I think the vast majority of them would actually opt for the roadside breath screening test, take their infringement notice, probably be suspended from driving for a period of 12 hours."
Mr Shadbolt said drivers would be less inconvenienced and officers could then stay on the road.
He said modern breath test machines were a lot more accurate and efficient than they were in the past.
Mr Shadbolt also questioned the need to carry out blood tests in most cases.
Law Society law reform committee member Graeme Edgeler raised concerns the bill would prevent drivers from opting for a blood test if they were caught between 250mcg and 400mcg in a breath test.
"The problem with the breath test is you can't challenge it," he said.
Blood tests enabled people to challenge the breath test results, he said. They also had to be paid for by the drink driver if they failed.
AA senior policy adviser Benjamin Young said it supported drivers having no right to a blood test if they were caught between the current and proposed new breath limit.
But the right to a blood test should remain if its removal was likely to result in successful legal challenges that could end up with people escaping sanctions altogether, he said.
