A European Commission spokesman has confirmed that the Government would have a problem if it wanted to ban incandescent light bulbs by the end of the year.
Environment Minister John Gormley has insisted that there is no disagreement between his department and the EU Commission.
The problem would emerge because under EU mutual recognition rules that govern the internal market, member states must allow the sale any product that is legally for sale in another member state.
That would make a ban in Ireland impossible since there would be nothing to stop a retailer sourcing incandescent light bulbs in another member state.
Speaking this evening, the Minister said that the rules of the EU's Internal Market could make exceptions in the case of environmentally progressive measures.
A comparison would be the energy drink Red Bull, which the French government wanted to ban on health grounds. But on legal advice it was found that since other member states sold the drink legally then the French could not apply a ban and the move was withdrawn.
A ban could only come into place if all other member states agreed and the restriction was agreed through the Council of Ministers.
Austria and Germany both wanted to bring in a ban after Australia announced a ban and the advice to those two countries was the same.
The European Commission has a policy of supporting energy saving light bulbs but it is not yet law.
The draft EU directive on the eco design of energy products is currently under discussion. It is aimed at increasing energy efficiency by adapting a range of electrical appliances, particularly those that have stand-by modes.
The directive has drawn together interested parties, from industry, member states, small and medium sized businesses and NGOs to find a way to ensure that electrical goods might in future be more energy efficient.
One option is phasing out incandescent light bulbs in 2009, but the industry, under the European Lamp Companies Federation, wants the phase out to be delayed until 2015.