AUGUSTA — Lawmakers grappled Tuesday with the question of whether to set a blood-level limit for marijuana that police could use to determine whether a driver is operating under the influence.

After nearly two hours of discussion, members of a legislative committee opted to delay a vote on a bill that would have established Maine’s first legal limit for how much of the hallucinogenic compound THC drivers can have in their bloodstream in order to be charged with OUI. Earlier Tuesday, the committee voted 8-5 to reject the bill, but the measure was quickly revived for potential changes.

Several committee members appeared to support stripping out the proposed legal limit – 5 nanograms of THC per milliliter of blood – while keeping other aspects of the bill.

Colorado and Washington – where recreational marijuana use is legal – as well as Montana have adopted a 5 nanogram limit for gauging whether a person is intoxicated. However, critics have questioned the science of the limit, and advocates for Maine’s medical marijuana users said the policy change could unfairly punish legal users who are not driving impaired.

Members of the Criminal Justice and Public Safety Committee raised other concerns about the bill as well.

One provision of the legislation, L.D. 1628, would extend Maine’s zero-tolerance policy for alcohol among underage drivers to marijuana as well. But critics suggested that could result in license revocation for legal medical marijuana users between ages 18 and 20 who were not impaired but were found to have marijuana in their bloodstream after they were stopped for another driving infraction.

Several committee members said they also hoped to amend the bill to require that law enforcement test for drugs – including marijuana – in the blood of drivers involved in fatal accidents. Police already test for alcohol after fatal crashes and request testing for the presence of drugs. But the proposed amendment would make the drug test mandatory in order to help inform future policy decisions on OUI issues.

The committee is expected to take up the bill again Thursday.