Not a single retailer has been prosecuted for selling cigarettes to underage customers in a dozen years, prompting claims the laws are a useless deterrent.
The Department of Health revealed the last time a retailer was prosecuted for selling cigarettes to someone aged under 18 years was in 2001.
Mike Daube, the president of the Australia Council on Smoking and Health, said it was time to start using the law to punish retailers who sold the lethal products to teens.
Professor Daube also called for new penalties to remove the licence to sell tobacco from repeat offenders, claiming there was ample anecdotal evidence to show it was happening.
"We know that smoking kills one in two of the regular users and we know most smokers start when they are young," he said.
"If there hasn't been a prosecution for 12 years then I don't think we are taking the law seriously enough.
"There is not a single retailer alive who doesn't know that cigarettes are lethal and that they shouldn't be selling to kids."
The law was once used actively, with 61 prosecutions between 1990 and 2001, according to the Health Department.
An undercover operation last year found nearly 40 per cent of retailers investigated sold to teenage customers.
But a Health Department spokesman said another sting in October last year found no retailers were in breach of the law, which Professor Daube claimed was not a realistic reflection of the situation.
Health Minister Kim Hames did not respond to allegations the laws were a useless deterrent.
He said he was serious about measures to reduce smoking, having introduced stringent non-smoking areas and restrictions on tobacco promotion.
He said the rate of smoking in young people had reduced dramatically from 18 per cent in 1996 to 6 per cent in 2011. In 1984, about one-third of adults in WA were smokers, compared with about one in 10 now.
"Enforcement agencies work hard to educate retailers about their obligations and legal responsibilities under the Act," he said.