Can I smoke pot and drive? What happens if I'm caught high behind the wheel? How will police test for drug impairment?

With just weeks until Canada becomes the second country in the world to legalize recreational use of marijuana, many questions remain unanswered about how the move will affect drivers.

CTV News teamed up with two medical cannabis users and the Delta Police Department in an effort to get the answers.

"It's given me my life back," said Cheryl McIntyre, who has been using cannabinoid oil on a daily basis since November to calm her tremors and deal with other chronic illnesses.

McIntyre said she doesn't drive after consuming cannabis and is worried about more people driving high once recreational use of the drug is legalized.

Mike Mann, on the other hand, has been smoking pot for the last 17 years to help ease the pain of his arthritis and considers himself functional enough to drive, despite using three to five grams of marijuana a day.

As part of CTV's investigation, McIntyre and Mann both agreed to undergo standard sobriety tests after using their cannabis products of choice.

Const. Grayson Smith, a drug recognition expert with the Delta police who administered the tests, asked both pot users to walk in a straight line.

McIntyre, who was tested an hour after she took cannabinoid oil, failed the sobriety test and said the experience "makes me definitely more aware of why I wouldn't drive."

Mann was tested shortly after smoking pot. Police also had concerns about his ability to safely operate a vehicle.

"We don't believe he's impaired, but affected enough that we could suspend his licence for 24 hours," said Delta police Chief Neil Dubord.

New provincial legislation will give police another option for dealing with these kinds of situations on the road: a 90-day driving ban for drug impairment.

"That's based on the results of a blood or a urine test or the drug recognition evaluation," said lawyer Kyla Lee.

Ottawa has also approved the use of a controversial roadside saliva screening device called the Dräger Drug Test 5000.

The device lets officers test drivers' saliva samples for the presence of THC—the active ingredient in marijuana that provides a high. The Dräger 5000 can also check for signs of amphetamines, opiates, cocaine, methadone and other substances.

But Lee and other are sounding the alarm about the potential drawbacks of the system.

Mann put his saliva in the Dräger 5000 and tested positive for THC even though it had been 10 hours since he'd smoked pot.

"This device could take someone off the road when they're not presenting any risk," Lee said. "People are going to be wrongfully punished and arrested."

Vancouver defence lawyer Paul Doroshenko put on a demonstration for local media earlier this month aimed at pointing out the device's flaws, namely the amount of time it takes to actually provide a result.

Lee said studies have shown THC can remain in someone's system for weeks after using marijuana, but that doesn't mean they're impaired at the time of testing.

Some haziness remains about when and how the Dräger 5000 will be used, but what's clear is that lawyers are poised to challenge laws in the new pot reality starting Oct. 17.

With files from CTV Vancouver's Mi-Jung Lee