Banning smoking in cars when children are present is 'excessive' and 'unnecessary', that's according to the smokers' group Forest.
On Tuesday, the Scottish Liberal Democrats lodged a bill at Holyrood calling for legislation to be brought into force to protect the health of youngsters.
If passed, smokers will be hit with a £100 fine if caught smoking in their vehicle whilst a child, under the age of 18, is present.
A number of countries have already legislated to ban smoking in vehicles while children are present, including Australia, Canada, South Africa and others.
According to smokers' group Forest, the move is a "gross intrusion on people's privacy".
Director Simon Clark said:
"The government is taking a sledgehammer to crack a nut.
"The overwhelming majority of smokers know smoking in a car with children is inconsiderate and they don't do it.
"The regulations are unnecessary and excessive. Do we really want to criminalise people for lighting a cigarette in a private vehicle?
"How will they be enforced? The police have better things to do than look for drivers smoking on the off chance there's a child in the car.
"The next step will be a ban on smoking in all private vehicles followed by measures to prevent smoking in the home.
"It's a gross intrusion on people's privacy."