Tcas? Priority over ATC instructions?

[sabenaboy]

The recent collision over Lake Constance in Germany, has demonstrated that it is vital that pilots obey TCAS Advisories even if ATC tells them to do exactly the opposite.

I have been trained to always obey the TCAS. However I am not able to find an official document published by ICAO or JAA, that stipulates that TCAS does indeed always takes precedence over ATC instructions.

Could someone please tell me where exactly this is written down. A link to an official document would be highly appreciated!

Thanks,
Sabenboy.