The requirement, stated exactly
General food law requires that food, and any substance intended to be incorporated into food, is traceable at all stages of production, processing and distribution. Operationally, that means each food business must have systems and procedures allowing them to identify the businesses from which they have been supplied, and the businesses to which their products have been supplied, and to make that information available to the competent authorities on demand.
The standard description of this is one step back, one step forward. A business must know its immediate supplier and its immediate customer. It is not required, under the general rule, to know where its supplier's inputs came from or where its customer's output goes.
There are more demanding requirements for particular sectors and products, where specific rules impose additional identification, marking or documentation obligations. But the general baseline is the paired link.
Why the rule is set at that level
A requirement for each business to trace a whole chain would be unworkable, because no business can compel disclosure from parties it does not deal with, and commercial confidentiality would prevent it even where it could.
The paired-link design solves that by making the chain reconstructable by an authority rather than visible to any participant. Each business holds two facts. An investigator with power to demand records from successive businesses can walk the chain in either direction by following those pairs.
The design has an elegant property: it distributes the record-keeping burden to the parties who already have the information, and centralises the reconstruction with the party who has the legal power to compel it.
It also has an obvious failure mode, which is the subject of the rest of this article.
| Party | Must be able to identify | Not required to know under the general rule |
|---|---|---|
| Primary producer | Who they supplied | The eventual retailer |
| Processor | Immediate suppliers and immediate customers | The origin of a supplier's own inputs |
| Broker or trader | Immediate suppliers and immediate customers | The chain beyond those |
| Manufacturer | Immediate suppliers and immediate customers | The full ingredient history |
| Retailer | Immediate suppliers | Individual consumers, who are excluded |
| Competent authority | Nothing in advance | It reconstructs the chain by compelling records |
Structure set out by this newsroom from the published rules named in the sources below. It is not a survey, a measurement or a market study.
Where the chain gets thin
The chain is made of records, so it is only as strong as the records.
Falsification. A deliberately falsified document does not break the chain visibly. It redirects it. An investigator following the pairs arrives somewhere plausible and wrong, and the discrepancy only appears through reconciliation against physical quantities or independent testing.
Mixing. Where inputs from many suppliers are combined, the output cannot be traced back to a single source. It can only be traced back to a set. This is inherent to commodity processing rather than a defect, and it is why traceability in bulk commodity chains is generally at the level of a batch and a period rather than a consignment.
Length and complexity. Every additional intermediary adds a link, and each link is a point at which the record can be wrong. Chains involving brokers and traders who never physically handle the goods are longer in documents than in logistics.
Cross-border complexity. Records maintained under different regimes, in different languages, held by businesses outside the jurisdiction, are harder to obtain and to verify.
Lot marking, the practical instrument
Traceability in practice runs on lot identification. A lot or batch number identifies a quantity of food produced or packaged under practically identical conditions, and specific rules require lot marking with defined exceptions.
The lot number is what makes a targeted withdrawal possible. Without it, a problem in one production run would require removing all product, because there would be no way to distinguish the affected units.
For a shopper the lot code is usually invisible in daily use and becomes visible exactly once: when a recall notice specifies which lot codes are affected. That is the moment the whole apparatus becomes concrete.
Beyond the legal minimum
Many supply chains operate traceability far beyond the legal baseline, for commercial rather than legal reasons.
Retailer specifications commonly require approved supplier lists, audit rights, testing regimes and mass balance reconciliation. Certification schemes impose their own chain of custody requirements, which for some schemes means tracking certified material through processing. Sectors where a specific integrity claim is being made generally build the verification the claim requires.
This is where most actual assurance sits. The legal requirement establishes a floor and a power of investigation. The commercial arrangements above it are what make a claim about origin or method meaningful in normal trading, and they are invisible from a pack.
Mass balance, the quiet workhorse
The single most effective verification technique in food supply chains is not testing. It is arithmetic.
Mass balance compares the quantity of an input a business could have obtained with the quantity of output it claims to have produced. If more certified, or organic, or origin-specific product leaves a site than could have entered it, the discrepancy is visible without any laboratory work.
This technique is why record-based auditing is more powerful than it appears from the outside, and why so much food fraud is detected through paperwork reconciliation rather than through analysis of the food.
Where this stops
This article describes a legal and commercial mechanism. It names no business and makes no claim about any company's chains. Where an actual incident is concerned, the Food Standards Agency and Food Standards Scotland publish alerts and are the authoritative sources, and the National Food Crime Unit handles serious cases of deception in food supply.