Have you ever recorded a conversation or shared a conversation that you've recorded? If the answer is "yes," there's a chance you may have committed a crime! In Michigan, it's a felony to use a device to record or transmit a conversation without the consent of all the participants. It's also a felony to share any information that you know was acquired through the illegal recording, or "eavesdropping," of a conversation.
Luckily, there is an important exception to the eavesdropping prohibition: In Michigan, we are free to record any conversation in which we participate. Whether that's a good idea, of course, is an entirely different matter! Based on the numerous lawsuits brought by individuals who were unhappy about their conversations having been secretly recorded, I would guess that many a family relationship or friendship has been lost over the issue.
There is another potential pitfall to keep in mind. While the recording of a particular conversation may be legal under Michigan's eavesdropping law, it may be illegal under a different Michigan law, or illegal under federal law (think "wiretapping") or the laws of another state.
So, unless you are absolutely sure about the legality of either using a device to record a conversation or sharing the contents of that conversation with others, or unless you are willing to risk breaking a relationship, it's wise to obtain the consent of all participants beforehand.