Interesting topic where there are many different aspects to consider and various opinions on it. Using EN 10204 and ISO 10474 as the basis of documentation requirements (yes I know this is really for metallic products) as there is no definitive standard defining documentation requirements then a CoC isn't required, a Declaration of Compliance is required and depending if it has a test report included it could be a 2.2, if no test report is included then it could be a 2.1. As a general rule of thumb where there is a breach of compliance to any document that has conformity at the end whether it be a certificate of conformity or declaration of conformity then this can be considered as criminal law. If there is a breach to a document ending in Compliance such as Declaration of Compliance then this can be considered as civil law. In other words compliance refers "to the best of our knowledge" and conformity implies "conformity to regulatory requirements". Further more there are certain standards such as API monogramming that allow for OEM's to create their own CoC as they place on the market. It gets more complex when you look at things globally as different countries have slightly different takes specifically the middle east regions.

I would say that depending on what industry you are in, consulting company legal counsel may be of benefit. If defects are noted in a resold vendor supplied item who is the liable party? Especially if there is no clear traceability and/or specifications.

@Andrew Conway - Thank you, Andrew. This is good and useful information.

@Ron Gilliland - Thank you, Ron. We did indeed seek legal counsel and they made some tweaks to the document we created. We now have a template to use when this comes up again.

It's more a question of financial risk and reward than of certification. Key question: why have you chosen to resell the parts? If making profit in the resale, the profits should be enough to offset your liability for quality costs. If to protect supportability or warranty of your product, you can do that with "to maintain warranty, use authorized parts only" messaging. If just doing it as a service to support the loyalty of your customers and the quality of the parts is not so great, it may not be worthwhile.

@Michael Faber, I work as a quality inspector but do a lot of quality assurance work. A certificate of compliance or conformance is a way to hold suppliers or vendors accountable for defective materials. It is a major concern in my department because our leadmen believe COC is not necessary, even though the material procedure required it. I strongly think COCs should state the standards and grade material is conforming to. There are COCs I've come across that only state the material type, but that does not mean the material met specific standard requirements.

An example, a COC might state 316L (lower carbon stainless steel) for material type. And mentioned that the material is in compliance with specifications. But the COC state no specifications like ASTM A312, or ASTM A479 that the material is conforming to.

If the definition of COC is meeting required standards, then I think it's important to state the standard of the material on a COC.

In your case, I think it will be best to confirm with your suppliers about material standards. The traceability of material is very important just in case something goes wrong. That is how we can trace back the history of the material to see what went wrong. Without traceability, it can be difficult to get to the root cause of defective material.

We are a distributor of industrial products and often supply what I'd call a "generic" COC on our own letterhead. If the need for further documentation comes up, we lean on our manufacturer.

@Michael Faber - You may want to look at ISO/IEC 17050 if you haven't already. I am not an expert in this standard, but I know some companies use this standard as their basis for declarations of conformity.