The only criteria that I�m aware of to make CAMS spec's is it must be within a certain manufactured date to be within the rule�s.
Hence why you see quite often second hand harnesses going for sale on rally forums as they are only good for lower clubman classes where the scrutineering has a bit of leniency for date of manufactured belts.
If a Cams sanctioned event requires the use of harnesses (eg. rallies, khanacross, circuit racing), then they must be either ADR, SFI or FIA certified and must not be past the expiry date set for that particular certification.
Even us plebs doing the smaller club rallies and khanacrosses still have to comply with the same rules as the big boys and the scrutineers are no more lenient as the rules are the rules.
If you are doing a CAMS sanctioned event which does NOT require harnesses (eg. motorkhanas, hill climbs, touring road events etc), then it is up to the Clerk of Course as to whether they will let you use them independant of whether the harnesses comply with CAMS requirements or not.
If you are doing an event which is sanctioned by someone other than Cams, then you will need to abide by their rules and requirements.
Here is the extract from the '08 CAMS manual for harnesses.
http://www.camsmanua...dule_I_Q308.pdf