In MN you don't have to advise the second party of the recording. I record a ton of conversations, including telephone conversations, and I save the digital recordings on my computer. It saved my butt this last week. I had a 16 year old kid that was being a real prick to some neighbors. Nothing really criminal, he just needed to be shaken up a bit. I called him on the phone and in a firm but professional matter told him to quit being a prick. He came in with his Dad two days later to file a complaint. He stated that I swore at him and threatened him. I was in the office and my supervisor came back and asked me about it. I told him that I was sending him an email with audio file attached to it. I asked him to play it to the kid and his Dad when he went back to his office. Needless to say they dropped the complaint.
Loyalty above all else, except honor.