This is good advice but remember that an illegal act is illegal regardless of who told you to do it. To take it to the extreme: Yes officer, I shot him but my boss told me to. I have a letter here prooving that I did not want to and that he overuled me...

The paper trail may get you out of trouble inside your company, but would be an admission that you knew you were wrong if the other company got hold of it. Tread with care - stay legal.