B.C.’s strict new drunk-driving penalties will come into effect Sept. 20, the government announced Wednesday.

As of that date, drivers who blow between 0.05 and 0.08 per cent blood-alcohol content into a roadside screening device will face increased driving bans and escalating fines, which the province describes as the toughest in Canada.

Drivers caught a first time in this “warn” range will receive a three-day driving ban and a $200 fine.

Penalties rise to a seven-day ban and a $300 fine on a second infraction, and a 30-day ban and a $400 fine on a third infraction.

If a driver fails the roadside screening test by blowing higher than 0.08, the new rules give police discretion to slap first-time offenders with a 90-day ban and a $500 fine.

The penalties are in addition to any charges under the Criminal Code.

Drivers may also be ordered to install an ignition-interlock device, which tests a motorist’s breath for alcohol content before the engine is permitted to start. If a driver fails the test, the vehicle is disabled.

The B.C. government passed the drunk-driving legislation in May without specifying a start date.

The government has acknowledged that it expects the new rules to be challenged in court. Critics have said the law lacks an effective appeal process, and that the roadside penalties give too much power to police to dispense punishment outside the court system.

Impaired driving offences rose 18 per cent in B.C. from 2008 to 2009, Statistics Canada reported last week. Provincial officials say alcohol-related crashes kill an average of 115 people and injure more than 3,000 every year.