Are dashboard video cameras legal??

Generally, anything that is relevant to litigation is discoverable. If there is evidence that leads to a finding of the facts, the courts typically allow it be discovered and introduced. So if you have a running GoPro on your dash, and your phone beeps announcing the receipt of a text message (caught on audio), and you pick up the phone to read the message (time message read recorded on phone) and you rear-end someone (video of accident caught on camera) while reading the text, chances are quite good that the lawyer for the other side is going to subpoena that GoPro video and your cell phone records and match them up. The lawyer may also subpoena the black box of your vehicle. So, drive safe out there!