A Supreme Court ruling has upheld the rights of provinces to impose tough drunk-driving laws, but has also establishes limits.

The court ruled today that B.C.'s tough regime that passed in 2010 needed more emphasis on police oversight and drivers' rights in two decisions addressing the issue.

One of the cases decided today was filed by Lee Wilson. The second case involved Richard Goodwin and a group of other drivers. Goodwin's case dealt with the constitutional issues.

While legal critics say today's rulings temper Canada's toughest drunk driving rules, the B.C. government says it is business as usual at roadside checks in the province, adding any constitutional challenges were fixed by 2012 amendments to the legislation.

B.C. Justice Minister Suzanne Anton said the immediate roadside prohibitions save lives.

"Our government believes strongly in our immediate roadside prohibition law and we know it saves lives — 260 since September 2010," said Anton. "I'm pleased to see the court agreed with our argument in the Wilson case and with the majority of our argument in the Goodwin case."

Legal experts who challenged B.C.'s five-year-old law said today's Supreme Court rulings guarantee a better balance between drivers' rights.

"The province's objective was a valid objective, but it needed to be balanced by charter rights," said Shea Coulson, a lawyer who argued automatic roadside prohibitions were unconstitutional.

"The court's biggest concern was that the device used by police was unreliable," said Coulson, adding that there were too few ways to challenge unreliable breathalyzer results.

In 2012 changes to the law ensured that every driver stopped in B.C. and breath tested would be offered a second test on an entirely different device by the officer involved. That was not always happening in the past.

In the more procedural ruling issued today the panel of judges underlined the importance of the use of breath tests to stop drunk drivers.

"It establishes a common standard for removing drivers from the road who pose an elevated risk to others. It also serves to deter drunk driving," said the ruling in the case of Lee Michael Wilson, released in Ottawa Friday.

B.C.'s tough instant prohibitions have a history of legal challenges.

In November 2014, Canada's highest court agreed to hear two cases involving B.C. drivers who were stopped by police at roadside checks. The case was heard in Canada's highest court in May 2015.

In one case, Wilson got a warning after blowing into a roadside screening device.

Wilson received a three-day driving ban in September 2012 after the roadside device registered a blood-alcohol level in the warning range.

He took the issue to B.C. Supreme Court, which dismissed the roadside prohibition, saying there was no evidence indicating Wilson's ability to drive was affected by alcohol.

But the B.C. Court of Appeal later overturned the lower court's ruling.

The other case involves James Goodwin and four other B.C. drivers who either refused to give a breath sample or registered a fail on a roadside screening device.

They challenged the province's automatic roadside prohibitions for those who blow over .08 on a screening device.

In Goodwin's case, court records say he did not provide a "suitable" breath sample after a stop in 2011.

Goodwin was prohibited from driving for 90 days and his vehicle was impounded for 30 days.

In Goodwin's case, the court ruled that search and seizure tests were met and the officers actions were reasonable.

"The ultimate question is whether the review provisions of the roadside suspension scheme offer reasonable protection against abusive exercise of the state power to intrude on the individual's private sphere, having regard to the nature of the scheme and the privacy interests at stake. In my view, the answer to this question is yes," said C.J. McLachlin, the chief justice who dissented from the other six on the constitutional issue.