My boss hired a lawyer, and the lawyer wrote a memo explaining that armed robbery was perfectly legal. There was really no way for me to know that armed robbery wasn't legal, and since my boss's lawyer issued his memo stating that armed robbery was legal, that's pretty much the end of the matter. I was acting in good faith, so I can't be prosecuted for any of the armed robberies I've committed, including the ones I committed before my boss's lawyer issued his memo. Likewise, my boss was acting in good faith, so he can't be prosecuted for ordering me to commit those armed robberies. And my boss's lawyer was acting in good faith, so he can't be prosecuted, or disbarred, or suffer any other penalty, for issuing a legal opinion that armed robbery was legal.
I hope this clears everything up.