The ruling from the European Court of Justice, which is supposed to apply only to tobacco products, is the most significant challenge to EU regulations since a tobacco-control directive was passed in 2006.
The ruling comes after the European Parliament, the Council and most countries agreed in 2013 to allow the EU to apply the ruling in a different way, but with an added element of uncertainty.
The European Parliament voted last year to let tobacco companies apply the tobacco product rule to cigarettes and to limit its applicability to smokeless tobacco, which have already been made legally available in EU countries.
The European Commission, the EU’s executive, has said that its Tobacco Products Directive will be applied only to smoke-free tobacco, and the European parliament has also said it would have no objection to the directive applying only to products containing nicotine.
However, the European Commission has said it is not aware of any new developments which could give rise to a new legal regime for e-cigarettes, which are not currently regulated.
EU rules require companies selling tobacco products to be registered with the European Food Safety Authority and to apply for permits to sell and store tobacco products.
This can be done by companies selling to individuals or by those selling to retailers.