That depends, was the engineer told "here is your spec", where the spec was they could have higher emissions than the law actually says, or was the engineer told here is the law, but you can ignore it if it gives us better numbers. In the first case the engineers who broke the law was mislead by those he should be able to trust to explain the law, while in the latter he knew he was part of breaking the law.

The law is generally written in legalese. It is really hard to understand how X volts on some sensor relates to emissions regulations. Therefore the engineers doing the work are easy to mislead, they probably don't even have access to sensor values that can directly tell you something in the law. Rather it is a mechanical engineer explaining that when the temperature is X and (pages of sensors they do have) you change these actuator settings. Give wrong information here and the engine will run as design and the programmer who made the mistake won't even know.