I believe all that is required is that one party know that the conversation is being recorded.
You do not have to have the other party's permission to tape a conversation you are having with them.
You are not required to inform an officer that you are taping a stop.
At least in Virginia....
However, I am not too certain of this information, so don't take it to heart.
The basic rule for recording is when an officer asks you to stop so he can speak with you, or the moment you see flashing lights in your rear-view mirror, you start the recording and hide away the recorder in a place that lets sound in.
This may help: http://www.articlesbase.com/national...us-431017.html
"The 37 states which allow one party consent recording of oral communications are: Alaska, Arkansas, Colorado, Georgia, Hawaii, Idaho, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Minnesota, Mississippi, Missouri, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, West Virginia, Wisconsin and Wyoming."