Should diesel emissions system violations be considered an exhaust defect?

Newer trucks are manufactured with emission control systems. Some owners either remove or modify these systems. If this is detected during a roadside inspection should this be an exhaust violation? If yes, does this now create a violation of a critical inspection item resulting in a CVSA decal not being issued?

Looking for the committee to discuss and provide an answer in order for this situation to be handled consistently by roadside officers.
Note: NSC 11b does address emission control systems.

Canada has a regulation in NSC 11B that the exhaust cannot be tampered with. Discussion about how enforcement can determine this roadside, such as with glider kits. Enforcement may not be able to identify which parts, if any, are missing from the system without proper training, however, in some jurisdictions in Canada, roadside inspectors are trained to detect delete kits/tampering, etc. This is like a shock absorber which is a violation in Canada but not in the US. There is no regulatory section in Part 393 that would allow the inspection and a violation to be written regarding the emission system. The consensus is we leave it alone in the United States, unless a state law addresses it. Canada may address it through relevant laws and it would be a critical inspection item under Exhaust (therefore, the vehicle, in Canada, would not obtain a CVSA decal if a violation of the emissions system was present in Canada). In no case, would this be an OOSC condition.