It is hard to believe that something so obviously sensible and beneficial has taken so long to enact into law. Indeed, it may take even longer yet. The draft legislation, known blandly as "Food information to consumers" is due to be debated today at the European Parliament, with a vote scheduled for tomorrow. All the signs are that the voting will be close; and it cannot be taken for granted that the clearest and simplest proposal for food labelling will even now win the day.

One way or another, the "traffic-light" system, devised by the Food Standards Agency, has been under consideration for years. And it does exactly what the name suggests: it colour-codes processed foods – red, amber and green – according to the levels of fat, saturated fat, salt and sugar they contain. Two British supermarkets, Asda and Sainsbury's, have adopted the system voluntarily. Many others, including Tesco, have not. If approved by the European Parliament this week, traffic-light labelling for processed food will become a statutory requirement across the European Union within three years.

The reason it has taken so long to advance even this far is simple. Many of the big food producers, including PepsiCo, Nestlé and Danone, oppose it and have spent enormous amounts of money and energy lobbying against it. They prefer either a basic calorie count, or a system known as Guideline Daily Amounts which measures the ingredients of processed food against recommended daily intakes. They insist that this allows consumers to exercise greater freedom of choice. The drawback – and, it hardly needs to be spelt out, the advantage for the manufacturers – is that it makes life more complicated for the shopper than the traffic-light system and may also give the impression that certain foods – breakfast cereals, say, or ready-meals – are less unhealthy than they really are.

The ferocity of Big Food's lobbying efforts should send its own message. Clearly, the manufacturers believe that the traffic-light labels would have a detrimental effect on sales, as consumers spend their money on healthier options. The effect could be especially marked in Britain, where processed and junk food has a larger market share than it does in many other European countries. But the food industry is not without a remedy. It has a choice, too. It could choose to produce food that merits fewer red lights, and so make what is easily the most consumer-friendly labelling system work to mutual advantage.