The state representative from Philadelphia admits he is breaking the law.

“I’m literally driving under the influence virtually every day,” said State Rep. Chris Rabb (D., Philadelphia). That’s because Rabb, like nearly 200,000 Pennsylvanians, is a state-approved medical marijuana patient.

Rabb takes his cannabis before bed. He is adamant that he doesn’t do it to get high. By the time he wakes up refreshed in the morning, he doesn’t even feel it.

But tiny amounts of THC, the psychoactive compound in cannabis, can remain in the blood for up to a month. And state law has a zero-tolerance limit for THC. Technically, that means Rabb is driving under the influence whenever he gets behind the wheel.

“What’s important to note is that that ‘influence’ does not impair me,” Rabb said. “I’m not driving recklessly. But that doesn’t matter to most police officers. Law enforcement has a dim view of any legalized cannabis use.”

Rabb serves the 200th Legislative District, which includes Mount Airy, in the State Assembly.

On Tuesday, Rabb introduced a bill to modify the existing state DUI statute. Currently the state forbids driving if there is “any amount” of a Schedule 1 controlled substance in the blood.

Cannabis still is considered by the federal government to be a Schedule 1 controlled substance, on par with heroin or LSD, despite a Pennsylvania law and a Department of Health program that promotes marijuana’s use to treat nearly two dozen ailments.

Rabb’s bill would amend the statute to provide an exemption for “marijuana used lawfully in accordance with the act ... known as the Medical Marijuana Act.”

Rabb’s bill has support from nearly a dozen Democrats in the Assembly, but there are no Republican co-sponsors yet.

Being under the influence is very different from being impaired, Rabb argues. And his bill would not allow marijuana users to drive when they’re impaired.

“Law enforcement can reasonably determine if someone is impaired through basic protocols,” he said. “It doesn’t matter what is impairing you. Sleeplessness can impair driving. Scores of pharmaceutical medicines can impair driving.

"I don’t care what a person is doing or ingesting, it’s the impairment that poses the danger. That’s what needs to be addressed.”

Marijuana advocates said the bill is an important step but may not go far enough.

“I have some concerns about the bill,” said Jeff Riedy, an organizer for the Lehigh County chapter of NORML, the National Organization for the Reform of Marijuana Laws.

“It doesn’t say how an officer is supposed to know if they’re patients. There needs to be some standards on how to test for impairment," Riedy said. “And there needs to be something included to make sure that police officers know the law exists if it passes.”

Several medical marijuana patients in Pennsylvania have been prosecuted for DUI. Usually, it’s because police stopped them while they were driving.

Arrested patients say that they volunteer information, thinking it will spare them a serious charge. They offer that they are registered with the state to use cannabis and show the officer their state-issued patient cards.

At that point, an officer has all the information needed to put on the handcuffs, and take the patient in for a blood or a urine test, patient advocates say. When a trace amount of THC is detected, patients are charged with DUI, lose their licenses for a year, and are subject to big fines or even jail time.

“We hear about quite a few cases. But we’re not sure exactly how many patients are fighting those charges,” said Riedy. “But not many have the money to combat those charges.”

Riedy said a similar bill, SB475, was introduced last year in the State Senate.