The number of police officers trained to recognize drug-impaired drivers is lagging far behind the number that police chiefs said would be needed after cannabis is made legal for recreational use nationwide on Oct. 17.

According to a senior government official, 833 Canadian police officers have been trained as drug recognition experts (DREs). That's a far cry from the 2,000 the Canadian Association of Chiefs of Police said should be trained to fulfil the government's push to crack down on drug-impaired drivers.

While the number of DRE-trained officers has increased by 50 per cent since last fall, government officials have said more work must be done to push that number higher.

Moreover, while the government has introduced three new criminal offences involving cannabis-impaired driving, they all require a positive blood test from a suspect before a Crown attorney can secure a conviction.

Right now, the vast majority of police forces across the country are not equipped to draw a blood sample at a police station or detachment. In fact, government officials said Friday they weren't aware of a single police service in the country capable of drawing blood at a station or detachment.

Officials said police forces could tap federal funding to hire nurses or a technician to draw the samples they need.

The three new drug-related offences — now in effect after Bill C-46 passed Parliament in June — are for drivers who have consumed drugs within two hours of driving.

A driver found to have at least two nanograms, and less than five nanograms, of THC per millilitre of blood could face a maximum fine of up to $1,000. (THC is the primary psychoactive found in cannabis.)

A driver caught with a blood THC level of more than five nanograms, or found to have been drinking alcohol and smoking cannabis at the same time, faces a fine and the prospect of jail time. In more serious cases, a drug-impaired driver can face up to 10 years behind bars if convicted.

Police who are certified DRE experts undergo a series of practical training sessions — a program developed by the International Association of Chiefs of Police — to help them identify drivers who are impaired but aren't under the influence of alcohol. The program is designed to enhance a police officer's ability to spot the common signs of drug use.

Unlike cannabis impairment, alcohol impairment is relatively easy to detect because there is a closer correlation between the results of drivers' breathalyzer tests and their blood alcohol levels.

While the government has given a green light to one oral fluid device — which can help road patrol police officers detect the presence of drugs — police services still need DRE-trained officers since not all drugs can be screened for at the roadside, and there isn't enough evidence to set limits for every substance.

A DRE-trained officer takes a suspected impaired driver through a 12-step process which includes physical tests, the collection of urine or saliva samples, if necessary, and questions to determine the driver's state of mind.

An assessment from a DRE-trained police officer could be enough on its own to level an impaired-driving charge against a driver under other, potentially less punitive Canadian laws that are meant to discourage people from driving while high.

Drug recognition experts are not the front-line officers trained to conduct Standardized Field Sobriety Tests (SFSTs) — roadside tests to identify drug-impaired drivers. Rather, DREs are trained to test drivers once they've already been stopped for a drug-impaired driving offence.

"We wish to, once again, assure all Canadians that failure to reach the target of 2,000 DREs in Canada does not prevent the police from being able to detect and deal with drug-impaired drivers today and once cannabis is legalized on October 17, 2018," the Canadian Association of Chiefs of Police said in a statement.

"Canadian police services are working diligently to increase the number of trained officers while ensuring that there is a strategic deployment of trained police officers across each jurisdiction."

After a fractious debate in Parliament and impassioned arguments between prohibitionists and those demanding a more permissive regime, recreational marijuana possession will be legal nationwide in two weeks' time.

The government is sending a postcard-size document to 14,000,000 Canadian households over the next two weeks. The document outlines some of the basics of Bill C-45, the Cannabis Act, including warnings about driving or working while high and the need to keep cannabis away from children, youth and pets.

It also warns of the potential health effects of ingesting cannabis and the risks involved in travelling with cannabis across the Canada-U.S. border.

Starting on Oct. 17, more and more Canadian travellers to the U.S. could be forced to answer an uncomfortable question by wary American customs officers: Have you ever smoked pot?

Those who tell the truth risk being banned from the United States for life and might have to apply for a special waiver in order to visit the U.S. in future.

Thousands of Canadians have been denied entry to the U.S. for cannabis use already, while others have been banned simply for admitting they've smoked a joint once in their lives. For American border guards, a confession is just as good as a conviction.

While some U.S. states have dismantled prohibition — including Washington, a border state — possession remains a criminal offence federally. And the U.S. border is governed by federal law.

It also will be illegal for travellers to bring cannabis to Canada from abroad.

New signs will be posted at the border warning travellers. A government official said Friday that all Canadian Border Services Agency (CBSA) guards will be required to ask each and every traveller about cannabis possession at the border, and a question about cannabis use will be added to the declaration forms travellers fill out when entering Canada by air.

While the federal government's legislation dismantles many of the criminal sanctions against the drug, it's up to individual provinces to decide on the practical details of cannabis sales, and rules on where and when someone can light up.

As with many aspects of law in the patchwork of Canadian federalism, the rules vary considerably depending on where you live. In general, the legal age has been harmonized with the current drinking ages: 18 or 19.

Ontario will restrict legal sales to an online portal until some point in the spring when private stores will be up and running (April has been tentatively suggested). The Ontario Cannabis Store, a government-owned entity, will be the exclusive wholesale and distributor to those stores.

Other provinces, like Quebec and most of Atlantic Canada, are pursuing a Crown corporation approach with distribution and sales controlled by an arm of the provincial government. In the West, retail sales will be handled largely by the private sector.

Municipalities will have leeway to implement their own bylaws on the location of stores and other local matters. Apartment buildings and condo boards will have their own restrictions, with many already opting for a restrictive stance banning cannabis consumption on their properties, both inside and out.