Under Spanish law, products containing herbal ingredients are classified as medicines unless they are included on a list of permitted plants drawn up in 1973.
The list was last updated over 30 years ago, since which a number of extracts have become available in other member states - such as guaraná, ginseng, espirulina and passiflore - but are systematically removed from the Spanish market in Spain.
If the EC is successful in its bid before the ECJ, it could open up considerable new opportunities for the sale of herbal supplements in Spain - giving suppliers access to the 40 million-strong Spanish population.
According to Euromonitor International, retail sales of herbal supplements in Spain totalled €63.2m in 2005, compared to €81.9m in Italy, €105.3m in the UK, €193.7m in France, and a massive €404m in Germany.
The market researcher predicts that Spanish sales will grow to €76.1m by 2010.
Spanish health product groups welcomed the 2002 dietary supplements directive as the first legal recognition of food supplements in the country, but herbals do not presently fall under the scope of this piece of legislation.
In fact, there have been some complex regulatory shifts over the last 30 years relating to herbals and the broader supplements category, but the current scenario is that a number of ingredients that were previously permitted are now not.
According to the EC, Spanish practice exceeds what is necessary in terms of public health, and the problem lies in restrictive interpretation of the relevant law.
Originally some products excluded from the 1973 list, such as ginseng, were initially permitted on the market under a far-reaching dietetic foods law from around the same time.
However this law was later replaced by Europe's Parnuts regulation, which created a much stricter definition of dietetic foods that left the likes of taurine, CoQ10, carnitine and isoflavones that were not on the market prior to Parnuts out in the cold, since they were not recognised by any law.
The situation was somewhat addressed by the 2002 supplements directive.
But since 2002 Spanish authorities have since 2002 decided to enforce a later regulation, published in 1990, to regulate herbals.
This law sought to create a 'traditional plants' category as distinct from registration drug products.
But having no references for traditional plants, the regulators have looked to the herbal preparations listed on the annex to the 1973 law, despite no mention of 'traditional' under this list.
For herbals not on this list, the, the only route to market is to gain permission for the plant to be sued as a medicine - a long, arduous and expensive path that, there can be little doubt, stifles new product development and product launches.
The EC has said it "considers the absence of adequate procedures for assessing the risk to public health allegedly posed by products containing plant extracts an unjustified and disproportionate barrier to intra-EU trade".