You need to edit the file as root, which is typically done by using 'gksu gedit' and then the file to edit. Better than editing the default rules - which Ubuntu doesn't like - would be to override the rule with one of your own. May I suggest something like this?
gksu gedit /etc/udev/rules.d/55-udev-user.rules
Add the lines specified by Brother:
# libusb device nodes
SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", ... , MODE="0666"
Save the file, exit gedit and reboot the computer.
I looked at these pages:
Scanner driver downloads:
http://solutions.brother.com/linux/e...nload_scn.html
Scanner driver instructions:
http://solutions.brother.com/linux/e..._scn1c.html#u9
I hope this helps.
Lex