A ban on smoking in public places is not justified by the risks to health from passive smoking, a committee of peers has said.
MPs overwhelmingly backed the ban
MPs voted in February by a huge margin to ban smoking from all pubs and private members' clubs in England.
The House of Lords Economic Affairs Committee says MPs failed to consider evidence that passive smoking is more risky in the home.
The anti-smoking group Ash said smoke in public places caused many deaths.
The Lords committee examined government and public attitudes to risk.
Its report calls on ministers to pay more attention to the risks to personal liberty posed by new legislation.
Singling out the public smoking ban, it argues that the aims of the legislation have not been made clear.
The report says that greater attention should have been given to scientific evidence, which it says suggests that passive smoking in public places is a relatively minor problem compared with passive smoking in the home.
The committee concludes that: "Failure to consider these matters properly has resulted in the introduction of a policy that appears to demonstrate a disproportionate response to the problem."
Lord Wakeham, chairman of the Economic Affairs Committee, said the government had failed properly to apply guidelines on risk assessment.
"We are also concerned that the government does not pay enough attention to the cumulative impact of legislation on personal freedom and choice."
Balance of evidence
Deborah Arnott, of the anti-smoking charity Action on Smoking and Health (Ash), said the scientific evidence on the harmful nature of secondhand smoke was "overwhelming".
She said the government's Scientific Committee on Smoking and Health had twice reviewed the evidence and found secondhand smoke to be a cause of lung cancer and heart disease.
Breathing other people's smoke in the workplace was estimated to cause around 600 premature deaths a year, she said.
Ms Arnott said: "The aims of the legislation are crystal clear: to improve public health by minimising people's exposure to a major carcinogen [cancer causing agent].
"The fact that more people may be exposed to smoke in the home than in public places does not mean that no action should be taken to protect people from exposure to smoke in the workplace and public places."
"Furthermore the evidence is that legislation to control smoke in workplaces helps to reduce smoking in the home."
Simon Clark, of the smoker's lobby group Forest, said MPs had been hoodwinked by exaggerated claims about the effects of passive smoking.
He said: "The threat of passive smoking is based on extremely dubious estimates, calculations and guesswork.
"The evidence is highly subjective and doesn't stand up to close scrutiny.
"If there is a risk it is very small and it certainly doesn't justify a ban on smoking in every pub, club and restaurant in the country."
The Lords committee also criticised the fact that more money had been spent on rail, rather than road safety.