MPs voted last week by 376 votes to 107 in favour of banning smoking while a child is present in cars.
In the Commons debate, Charles Walker said: "It would be appalling if people who have been good parents in every other way found themselves being criminalised as a result of smoking in a car when their children were present," he said.
"We should guard against that," he added.
The idea was proposed by Labour and backed by the Lords.
Although the vote allows the new laws to be passed, rather than obliging the Government to take action, it is expected the measures will become law.
But Mr Walker, a teetotal non-smoker, added that there was "an enormous degree of hypocrisy" in targeting smokers.
He said alcohol was a far greater blight on society.
Mr Walker added: "There are many people in this place who want to ban smoking because they think it is not done by very nice people, but they are much more relaxed about alcohol because of their own habits."
Comment: Not only is there no real science to back up any claims that 2nd or 3rd hand smoke is dangerous, the anti tobacco cult and their junk science have succeded in tarnishing a perfectly healthy plant and way of stimulating our neuroreceptors.
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