Bro law and order explains this to five year olds, you should know how dumb that argument is.
In the criminal justice system, the people are represented by two separate yet equally important groups: the police, who investigate crime; and the district attorneys, who prosecute the offenders. These are their stories.
Implying that the executive doesn’t need to know law is crazy, every branch of government utilizes the law but one can only make law and the other can only enforce it.
Ignorance of the law isn’t an excuse from the law unless you work for the government and then reasonable mistakes are somehow reasonable to make. Ie. The government can get away with ignorant criminality and use it as a defense but you and I cannot, that’s not ok.