"We've sent a forceful message with these new measures," said Transportation Minister Michael McLeod. "If you drink and drive, be prepared to pay a heavier price."
The new law lowers the acceptable limit of alcohol in a driver's system to 0.05 from 0.08.
Motorists with alcohol-related offences on their record could also be required to take a safe driving class and submit to a substance abuse assessment before they are allowed to drive again.
"The legislation places an emphasis on curbing repeat offences and using medical assessments to identify potential problems with respect to substance abuse," according to a news release from the government.
The measures, among the first of their kind in the country, come on the heels of statistics that show the rate of impaired driving in the NWT is nearly five times the national average.
In total, 311 people were charged with the crime in 2002, a 22 per cent jump over the previous year, according to Statistics Canada.
During the same period, the national average dropped nearly five per cent. The only other province or territory to post an increase was Yukon.
The new laws should have immediate impact on those numbers said RCMP Staff Sgt. Steve McVarnock, who is in charge of the Yellowknife detachment.
"We have seen a number of repeat offenders," he said. "This will serve as a wake-up call."
Police now have the authority to suspend a motorist's licence for 24 hours if their blood alcohol content is between .05 and .079.
A second offence within two years can result in a 30-day suspension.
Novice drivers caught with alcohol in their system will automatically have their licence suspended for 30 days.
The lower threshold brings the territory in line with other jurisdictions in Canada, said Bob Kelly, manager of public affairs with the department of transportation. The new legislation does not affect federal law that governs drunk driving.
Motorists with a blood alcohol level between 0.05 and 0.079 will be given a ticket, but cannot be charged under the Criminal Code.