No, ISO GPS is not, in itself, a legal requirement. ISO GPS becomes binding primarily when it is referred to in drawings, contracts, customer specifications, terms of delivery or internal company standards.
Furthermore, ISO GPS can play a role in technical and legal assessment issues, for example when determining whether a product has been designed in accordance with recognised rules of the art. Of particular importance here is the principle of invocation set out in ISO 8015. This states that the use of even a single ISO-GPS specification implies that all rules of the ISO-GPS system are accepted for the interpretation of that specification.
Is ISO GPS required by law?
As a general rule, standards are not laws. ISO GPS is therefore not automatically a legal requirement for every company or every component. However, this does not mean that ISO GPS is optional.
Standards may become binding if they are referred to in contracts, drawings, purchase orders, specifications, quality agreements or customer requirements. In such cases, the binding nature does not necessarily arise directly from a law, but from the specific technical or contractual agreement.
Put simply: ISO GPS is not a general legal requirement, but it may be binding in specific business situations.
What role does product liability play in the ISO GPS system?
However, a look at product liability shows that technical responsibility does not begin with the manufacturing stage. Products must be safely specified, developed, manufactured and placed on the market. Technical standards play an important role in this regard, as they set out recognised rules and established procedures.
The ISO GPS system is the only valid standardisation system for geometric product specification that has been developed internationally by representatives of several countries. It can therefore be used as a general benchmark for the state of the art when assessing technical requirements and potential liability issues.
This is particularly important in the case of components that are critical in terms of safety, functionality or quality. Unclear drawings, contradictory requirements or specifications that cannot be verified may lead to significant technical and financial problems later on.
When will ISO GPS become mandatory?
ISO GPS becomes mandatory, in particular, when it is referred to in technical documentation. This may be done explicitly by means of a reference to the standard, or through the use of ISO GPS symbols and geometric tolerances.
This point is particularly important for technical drawings. Where an ISO-GPS standard, a GPS symbol or a geometric tolerance is used, this specification must not be considered in isolation. It must be viewed in the context of the relevant rules of the ISO-GPS system.
What happens if ‘ISO GPS’ is written on the drawing?
When ISO GPS is used on a drawing, all parties involved must be able to process and interpret the information correctly. This applies not only to design engineers, but also to production, metrology, quality assurance, procurement and suppliers.
An example: A bore may have the correct diameter but still be in the wrong position. A simple plus-minus tolerance does not adequately describe this geometric relationship, as the figure below shows. It is unclear which distance on the actual component is actually being assessed. A positional tolerance with a reference system, on the other hand, can specify this unambiguously.
Conclusion: Is ISO GPS compulsory?
ISO GPS is not automatically a legal requirement. ISO GPS becomes binding primarily when it is referred to in drawings, contracts, customer specifications, terms of delivery or internal standards.
Regardless of the formal requirement, ISO GPS is an important tool for clear technical communication. The principles of invocation and accountability in particular make it clear that anyone using ISO GPS should be aware of the rules and responsibilities associated with it.
So the better question is often not: „Is ISO GPS compulsory?“
Rather: „Can we afford not to understand ISO GPS when our drawings, customers or suppliers are already using it?“
Please note: This article is intended to provide technical guidance and is not a substitute for legal advice.
Further reading:
DIN: Legal binding force through standards – An overview of when standards are voluntary and when they may become binding through laws, regulations or contracts.
EUR-Lex: Directive (EU) 2024/2853 on liability for defective products – the current European legal framework on product liability and liability for defective products.