I am starting to seriously consider getting a dashcam.
Make sure it's hidden, the cops find it, it will disappear just like their dashcam videos do when they are at fault. Get a voice recorder too.
Get your technician ham radio license + APRS (www.aprs.fi) tracking gear and a dashcam, and you can transmit the images/data/voice to an off-site FTP server in case the cops "accidentally" destroy/lose your hard/drive or SIM card during a "cursory search of your vehicle".
If a cop is willing to lie to get you in trouble, he/she is willing to destroy evidence that will exonerate you.
Now you know why so many Russians have dash cams!
Timetec Road Hawk
http://www.amazon.com/Timetec-Windshield-Dashboard-Camcorder-Microphone/dp/B00CXB186Y
I am starting to seriously consider getting a dashcam.