They are legal but it's normally down to the hardware manufacturer of your bluetooth dongle to wether they use them or not. Some manufacturers decide to use them and others use the Windows drivers. It also depends on your OS. I have a bluetooth dongle that works on my mac but does not support the audio profile. I can download the WIDDCOM drivers for Win XP but that doesn't help me on the Mac side!
Best to check the website of your manufacturer. D-Link for example will supply the WIDDCOM drivers for some dongles.