The body representing solicitors says it is opposed to moves to introduce plain packing for cigarettes, arguing it would have a damaging effect on areas such as intellectual property rights.
The Law Society also predicted it could potentially lead to court challenges as well as a possible rise in smuggling.
Ken Murphy, its director general, is among a number of representatives who are giving their views to the Joint Oireachtas Committee on Health and Children on the proposed measure aimed at reducing rates of smoking.
A number of its solicitor firms would have acted for large tobacco companies .
Steven Donaldson told the committee that there there is no credible evidence to suggest that plain packaging will reduce smoking rates.
Extensive research has been carried out into why people take up smoking. All this research points to parental influence, peer influence, social and cultural norms, price and access as the key factors and not packaging, he insisted.
"Evidence offered by advocates for plain packaging point to a range of studies on attitudes and intentions to support their claims, but fail to point to any real world evidence on the effect on smoking behaviour, " he added.
"Studies referenced by Minister Reilly deal only with how people intend to react to the idea of plain packs, not what they actually do as a result of plain packs in the real world "Studies have shown that uglier packs are less attractive, but they have failed to make the critical connection between uglier packs and the decision to take up smoking.
"The evidence offered in favour of plain packs is analysed in detail in our submission, which I would encourage committee members to consider if they haven’t already.
"Australia is the only country in the world to introduce plain packaging,in late 2012. The evidence from Australia has demonstrated that the desired outcome of a reduction in smoking prevalence has not been achieved "The evidence that is available from Australia in reports from independent researchers KPMG and London Economics shows that smoking rates in Australia have remained on trend, with a small nnual decline.
"In fact, the incidence of smoking is declining at a slightly slower rate than in the previous ten years," he added.
By making it harder for smokers to distinguish between brands, price will become a more important factor. More people will turn to the cheapest available cigarettes. And these will be found on the black market, he claimed.
Previous evidence to the committee from gardai and the Revenue Commissioners cast doubt on claims that it would lead to more smuggling and both backed the measures along with a large group of doctors.