People can get very particular about their drink. In Dr No, James Bond famously says: "I would like a medium vodka dry martini - with a slice of lemon peel. Shaken, not stirred." He goes on to stipulate that her prefers Russian or Polish vodka.

What does this have to do with the law? Well, while it may seem trivial, the legal definition of what constitutes a particular type of food or drink can underpin entire markets, with millions of pounds depending on a few words.

The European Union, in its efforts to safeguard the reputation of its traditional drinks on the world market, regulates such definitions tightly. Recently, the European Parliament rejected a bid by countries including Poland, Finland, Sweden and Denmark to restrict the legal definition of vodka.

These "vodka belt" countries objected to the fact that ingredients other than potatoes or grain - such as sugar beet, grapes or citrus fruit - were used by other countries to produce the drink. They instead wanted the legal definition to be more like a shot and less like a cocktail.

A lot was riding on it. Globally, vodka sales are worth $12 billion (£6 billion) a year - some part of which is no doubt consumed in the legislatures of Europe. (As George Bernard Shaw observed, alcohol "enables Parliament to do things at eleven at night that no sane person would do at eleven in the morning".)

Unfortunately for the vodka belt countries, a rule was passed endorsing the existing practice of allowing ingredients other than potatoes and grain to be used in production, leaving them to despair in the belief that the vodka of other nations is never pure and rarely simple. The decision was, on the other hand, a victory for the UK, allowing it to maintain its position as the world's second-largest vodka producer after Russia.

By contrast - and for no good discernible legal reason - the new spirit labelling rules take a purist approach to whisky. That drink, the rules say, cannot contain flavourings or sweeteners or additives other than plain caramel used for colouring. So, while the vodka purists lost their legal argument, and vodka can contain contested ingredients, the whisky purists won theirs. To earn its lucrative name whisky must be pure. Why the pursists lost in one case and won in the other is an interesting question, but we can only speculate as to the political lobyying that took place behind the scenes.

The EU has a history of getting worked up over the legal definitions of food and drink. Take a 1979 a case known as Cassis de Dijon. German law had prohibited the marketing of liqueurs with an alcoholic strength of less than 32 per cent alcohol content. That made it impossible for a French company to export into Germany consignments of Cassis de Dijon, a French blackcurrant liqueur commonly mixed with white wine, with a strength of between 15 and 20 per cent alcohol. The French liqueur therefore wasn't allowed to compete with stronger German liqueurs in the German market.

The German government argued that it needed the rule excluding weak alcoholic spirits as part of a strategy against alcoholism. It argued, rather oddly, that if weak French spirits were available in Germany, German drinkers would be easily lured towards addiction. It said the consumption of French Cassis de Dijon would induce incremental tolerance to alcohol. The European Court of Justice rejected that argument, noting that many weak alcoholic drinks were commonly available in Germany.

The court said that the German regulations that had the effect of excluding Cassis were incompatible with European law on the free movement of goods. Any product lawfully produced in one country must, in principle, be marketable in any other member state. Only something important like the promotion of public health would be a sufficient reason to impose product conditions that would effectively restrict imports.

Comparable legal quibbles have also stirred the world of chocolate. Although commonly enjoyed as an ecstatic pleasure, the confection's legal definition is decidedly dispassionate. European law defines chocolate in a precise formula beginning: "the product obtained from cocoa nib, cocoa mass, cocoa powder . . . without prejudice to the definition of chocolate vermicelli, gianduja nut chocolate and couverture chocolate".

In a case in 2003, the European court ruled that it was permissible for a product containing up to five per cent of its weight in vegetable fat other than cocoa butter to be described as chocolate. The court ruled that Spain and Italy were therefore in breach of European law on the free movement of goods in insisting that British confectionary be labelled as "chocolate substitute".

As with vodka, the sheer volume of sales meant there was more to stake than mere words. The market for chocolate in Europe is worth £4 billion a year, with 16 of the world's top 20 top chocolate-consuming countries. Rarely in human history have such sober and trim legal definitions been the gateways to so much revelry and indulgence.

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