Plans for new drug driving limits in Scotland
New drug driving limits will help improve road safety in Scotland, Justice Secretary Kenny MacAskill said.
The UK government has launched a consultation aimed at making it easier to prosecute people who drive under the influence of drugs.
Zero tolerance is proposed for eight illegal drugs, including cannabis, ecstasy, cocaine, LSD and heroin.
The Scottish government would set the new limit but general responsibility would remain with Westminster.
Scottish Justice Secretary Kenny MacAskill said it would have been preferable for all power over the proposed new offence to be given to Holyrood.
Limits would also be set for econtrolled drugs that have widespread medical use but can also affect a person's ability to drive, such as temazepam, diazepam and methadone.
The proposals seek to end an anomaly which means that being on the roads after taking an illegal drug is only an offence if police prove that driving was impaired.
The consultation will cover Scotland but, depending on the responses received, ministers at Holyrood may adopt a different approach from Westminster.
The Scottish government has already set out plans to reduce the drink driving limit.
Mr MacAskill said: "The Scottish government is determined to do everything we can to make our roads safer and save lives. We have already announced our intention to lower the drink drive limit, but we must not lose sight of the problems caused by drug drivers.
"In line with our approach on drink driving, it may have been preferable to devolve all responsibility relating to the new drug driving offence.
"Nonetheless, having the power to set drug driving limits is a useful responsibility to have as part of our desire to improve road safety in Scotland."
UK Roads Minister Stephen Hammond said the proposed approach sends a clear message that driving under the influence of illegal drugs will not be tolerated.
But he said that setting limits for controlled drugs would clarify the position for those who need to take medication.
Mr Hammond explained: "We know that the vast majority of people who use these drugs are doing so responsibly and safely and that is why our approach does not unduly penalise drivers who have taken properly prescribed medicines.
"Together, these proposals will make our roads safer for everyone by making it easier for the police to tackle those who drive after taking illegal drugs and clarifying the position for those who take medication.
"Drug driving is a menace which devastates families and ruins lives."