Tobacco firms claim the Government's push for plain cigarette packets will not work – and will cost Ireland jobs.
Representatives of PJ Carroll, John Player and Japan Tobacco are appearing before TDs at the Oireachtas Health Committee today.
They claim there is no "credible evidence" to suggest that plain packaging carrying graphic health warnings will discourage children from smoking.
The HSE said plain packaging should be introduced as soon as possible, while Gardaí and the Revenue report it will not have any major impact on the black market.
But Steven Donaldson of PJ Carroll said it will damage Ireland as a business environment, and cost jobs.
"This legislation will not achieve its aims, but will have serious negative consequence."
"These include: boosting an already thriving black market, which undermines health objectives; costing the taxpayer further millions in lost taxes; costing jobs around the country; illegally confiscating intellectual property - and severely damaging Ireland's reputation as a result."