Police officers in Canada who lawfully pull over a driver no longer need reasonable grounds to demand a sample of their breath.

New changes in the Criminal Code that came into effect Tuesday give officers more authority when screening drivers for alcohol in hopes of reducing impaired driving and the number of deadly collisions.

Previously, when a driver was pulled over at a checkpoint or for violating traffic laws, an officer needed reasonable suspicion to request a breath sample to determine blood alcohol concentration.

Suspicion could arise from the smell of alcohol on their breath, slurred speech or strange behaviour from the driver.

"Officers will no longer have to articulate that suspicion," said Const. Chad Morrison of the Nova Scotia RCMP.

"If an officer is roadside with a vehicle, they will automatically have the authority to make a demand to any driver to provide a sample of their breath."

Anissa MacLeod of MADD Canada said the new legislation is a 'very big deal.' (CBC)

MADD Canada has been working to get a mandatory alcohol screening law into effect for 20 years, said Anissa MacLeod, the organization's Atlantic director.

Countries including New Zealand and Australia have similar legislation to help discourage impaired driving.

"We are really excited and thankful that this is coming into effect," said MacLeod.

"We know from examining other countries where they use mandatory alcohol screening, that it's had a huge effect on deterring individuals from driving while impaired, and it has reduced impaired driving considerably."

MacLeod said MADD suspects the new legislation, enacted with Bill C-46, will decrease impaired driving by as much as 20 per cent — or about 200 lives every year.

'Every expectation' new law will be challenged

Some legal experts, however, feel that the new legislation is likely to be challenged in the courts for being too broad. Under the Charter of Rights and Freedoms, "everyone has the right to be secure against unreasonable search or seizure."

Toronto-based lawyer Michael Engel, who often defends those charged with impaired driving, said the new rules raise concerns about baseless searches.

"This is a radical departure from previous law, which insulated people against warrantless searches without probable cause," he said.

The new rules could lead to a backlog in the legal system as lower courts wait for higher courts to make a decision on likely challenges to the law's constitutionality, he said.

"It's a brave new world," Engel said. "This is a wholesale change to the Criminal Code."

Civil rights organizations have also sounded alarms about the new rules, with the Canadian Civil Liberties Association expressing concern that mandatory alcohol screening will unfairly affect racial minorities who are disproportionately singled out by police for traffic stops.

Justice Minister Jody Wilson-Raybould has said she has "every expectation" the law will be challenged in the courts, Wilson-Raybould said she believes it's in line with the charter and would pass the legal test.

Morrison said he believes "most drivers who come into contact with police will be screened" but an exception to that could be a busy checkpoint where obtaining a breath sample from every driver would be time consuming and create long delays.

RCMP Const. Chad Morrison of Nova Scotia RCMP says the law 'has been credited with reducing impaired driving and fatal collisions around the world.' (RCMP Nova Scotia facebook page)

Officers performing checkpoints and other traffic initiatives will be expected to establish criteria for using their new authority ahead of time, including the frequency with which they are checking vehicles, said Morrison.

He said it's critical officers are documenting their procedures and actions "so there's no accusations that they are targeting any specific person or type of group of people."

Morrison said officers will also undergo updated ethics and fairness training.

"Our training and policies are hoping to address the concern that [mandatory alcohol screening] could be used as a means of police targeting certain marginalized groups," he said.

"We are just making sure that officers are using it in a fair ethical way."